Method of driving liquid ejecting apparatus and liquid ejecting apparatus

Abstract

To provide a driving method of a liquid jetting apparatus capable of obtaining desired discharge characteristics even when the state of a liquid is changed, and the liquid jetting apparatus.SOLUTION: A discharge section 2 including a nozzle, a pressure chamber communicating with the nozzle, and a drive element, wherein the drive signal has a discharge pulse, and the discharge pulse includes an expansion element that changes in potential so as to expand the pressure chamber and a contraction element that changes in potential so as to contract the pressure chamber expanded by the re-expansion element, when the acquired liquid information is first information corresponding to a first viscosity, a first discharge pulse in which a potential change width of the expansion element and a potential change width of the contraction element are set to be equal is supplied to the drive element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second discharge pulse in which a potential change width of the expansion element and a potential change width of the contraction element are set to be different is supplied to the drive element.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for driving a liquid ejecting device having a discharge portion that ejects liquid from a nozzle, and the liquid ejecting device, and more particularly to a method for driving an ink jet recording device that ejects ink as the liquid, and the ink jet recording device. [Background technology]

[0002] 2. Description of the Related Art A liquid ejecting apparatus, typified by an ink jet recording apparatus such as an ink jet printer or a plotter, includes a discharge unit capable of discharging a liquid such as ink stored in a cartridge or a tank.

[0003] The ejection unit includes a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and a drive element for generating pressure fluctuations in the liquid in the pressure chamber. The drive signal supplied to the drive element includes an ejection pulse having an expansion element that changes the potential to expand the volume of the pressure chamber, and a contraction element that contracts the volume of the pressure chamber expanded by the expansion element, causing the liquid to be ejected as droplets from the nozzle. A liquid ejection device has been provided that improves ejection characteristics by adjusting the amount of potential change in the ejection pulse according to the viscosity of the ink (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-20408 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the viscosity of the liquid changes significantly, simply adjusting the amount of potential change in the ejection pulse may not result in the desired ejection characteristics, such as the desired flight speed and ejection amount (weight), or may result in ejection failure, where the liquid is not ejected. [Means for solving the problem]

[0006] An aspect of the present invention that solves the above problem is a method for driving a liquid ejection device having an ejection section including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, the ejection pulse including an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber that has been expanded by the re-expansion element, and The method for driving a liquid injection device is characterized in that the starting potential of the contraction element is equal to the starting potential of the expansion element, and the waveform shape of the ejection pulse is set according to the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, a first ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set equal is supplied to the driving element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to different potentials is supplied to the driving element.

[0007] Another aspect of the present invention is a method for driving a liquid ejection device having an ejection section including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, the ejection pulse including an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element, and The method for driving a liquid injection device is characterized in that the waveform shape of the ejection pulse is set according to the acquired liquid information, and the starting potential of the ejection pulse is equal to the starting potential of the original, and when the acquired liquid information is third information corresponding to a third viscosity, a third ejection pulse in which the potential change width of the expansion element is set smaller than the potential change width of the contraction element is supplied to the drive element, and when the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity, a fourth ejection pulse in which the potential change width of the expansion element is set larger than the potential change width of the contraction element is supplied to the drive element.

[0008] Another aspect of the present invention is a method for driving a liquid ejection device having an ejection section including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, the ejection pulse including an expansion element that changes potential to expand the pressure chamber, a contraction element that changes potential to contract the pressure chamber expanded by the expansion element, and a re-expansion element that changes potential to expand the pressure chamber contracted by the contraction element, wherein an end potential of the expansion element and a start potential of the contraction element are equal, a terminal potential of the element and a starting potential of the re-expansion element are equal, the waveform shape of the ejection pulse is set according to the acquired liquid information, when the acquired liquid information is first information corresponding to a first viscosity, the potential change width of the expansion element and the potential change width of the contraction element are set equal, and a first ejection pulse having a re-contraction element whose potential changes so as to contract the pressure chamber expanded by the re-expansion element is supplied to the drive element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to different potentials is supplied to the drive element.

[0009] Another aspect of the present invention is a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has a discharge pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the discharge pulse includes an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element, and The liquid injection device is characterized in that the potential and the starting potential of the contraction element are equal, and the control unit sets the waveform shape of the ejection pulse according to the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, it supplies to the driving element a first ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to be equal, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, it supplies to the driving element a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to be different.

[0010] Another aspect of the present invention is a device comprising a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, an ejection unit that includes a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse includes an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element, and The liquid injection device is characterized in that the end potential of the expansion element is equal to the starting potential of the contraction element, and the control unit sets the waveform shape of the ejection pulse according to the acquired liquid information, and when the acquired liquid information is third information corresponding to a third viscosity, the control unit supplies to the drive element a third ejection pulse in which the potential change width of the expansion element is set smaller than the potential change width of the contraction element, and when the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity, the control unit supplies to the drive element a fourth ejection pulse in which the potential change width of the expansion element is set larger than the potential change width of the contraction element.

[0011] Another aspect of the present invention is a control device that includes a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, an ejection unit that includes a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse includes an expansion element that changes potential to expand the pressure chamber, a contraction element that changes potential to contract the pressure chamber expanded by the expansion element, and a re-expansion element that changes potential to expand the pressure chamber contracted by the contraction element, and wherein an end potential of the expansion element and a start potential of the contraction element are The liquid ejection device is characterized in that the potential change width of the expansion element and the potential change width of the contraction element are equal, the terminal potential of the contraction element and the starting potential of the re-expansion element are equal, and the control unit sets the waveform shape of the ejection pulse according to the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, the control unit supplies to the drive element a first ejection pulse having a re-contraction element whose potential changes so as to contract the pressure chamber expanded by the re-expansion element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, the control unit supplies to the drive element a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to different potentials. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic configuration of a liquid ejecting apparatus according to a first embodiment. [Figure 2] 3 is a cross-sectional view of a discharge section according to the first embodiment. FIG. [Figure 3] 2 is a block diagram showing the electrical configuration of the liquid ejecting device according to the first embodiment. FIG. [Figure 4] 3 is a block diagram showing a function realization unit of a control unit according to the first embodiment. FIG. [Figure 5] FIG. 3 is a waveform diagram showing an ejection pulse according to the first embodiment. [Figure 6]FIG. 3 is a waveform diagram showing an ejection pulse according to the first embodiment. [Figure 7] FIG. 3 is a waveform diagram showing an ejection pulse according to the first embodiment. [Figure 8] FIG. 3 is a waveform diagram showing an ejection pulse according to the first embodiment. [Figure 9] 4 is a graph showing the relationship between viscosity and the ratio of the width of potential change according to the first embodiment. [Figure 10] 10 is a graph showing the relationship between ink viscosity and the ratio of the potential change width for comparison. [Figure 11] FIG. 10 is a waveform diagram showing an ejection pulse according to the second embodiment. [Figure 12] FIG. 10 is a waveform diagram showing an ejection pulse according to the second embodiment. [Figure 13] FIG. 10 is a waveform diagram showing an ejection pulse according to the second embodiment. [Figure 14] FIG. 10 is a waveform diagram showing an ejection pulse according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below based on embodiments. However, the following description illustrates one aspect of the present invention and can be modified as desired within the scope of the present invention. In each drawing, the same reference numerals indicate the same components, and their description will be omitted as appropriate. In each drawing, X, Y, and Z represent three spatial axes that are orthogonal to each other. In this specification, the directions along these axes are referred to as the X direction, Y direction, and Z direction. In each drawing, the direction indicated by the arrow is the positive (+) direction, and the direction opposite the arrow is the negative (-) direction. The Z direction indicates the vertical direction, the +Z direction indicates a vertically downward direction, and the -Z direction indicates a vertically upward direction. Furthermore, the directions of the three spatial axes, which are not limited to positive and negative directions, will be described as the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0014] (Embodiment 1) FIG. 1 is a diagram showing a schematic configuration of a liquid ejecting apparatus 1 of the present invention.

[0015] As shown in the figure, the liquid ejecting device 1 is a so-called serial printer that includes a discharge unit 2 and prints by conveying a medium S in the X-axis direction while reciprocating the discharge unit 2 in the Y-axis direction and discharging (also called spraying) liquid from the discharge unit 2 toward the medium S in the +Z direction. Note that the medium S can be made of any material, such as recording paper, resin film, cloth, etc.

[0016] The liquid ejecting device 1 includes a discharge unit 2, a liquid storage unit 3, a control unit 4, a transport mechanism 5 that feeds the medium S, and a movement mechanism 6.

[0017] The ejection unit 2 ejects ink, which is an example of a liquid supplied from the liquid storage unit 3, in the form of ink droplets in the +Z direction.

[0018] The liquid storage unit 3 stores the ink to be ejected from the ejection unit 2. Examples of the liquid storage unit 3 include a cartridge that is detachable from the liquid ejection device 1, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. Although not specifically shown, the liquid storage unit 3 may store multiple types of ink, each with different colors or ingredients, individually. The liquid storage unit 3 may also be separated into a main tank and a sub-tank. The sub-tank may be connected to the ejection unit 2, and ink consumed when the ejection unit 2 ejects ink may be replenished from the main tank to the sub-tank. Ink may also be circulated between the liquid storage unit 3 and the ejection unit 2.

[0019] The control unit 4 includes, for example, a control device such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage device such as a semiconductor memory. The control unit 4 also includes a power supply device that supplies power from an external power source such as a commercial power source to each element of the liquid ejection device 1. The control unit 4 is electrically connected to the ejection unit 2 via external wiring (not shown). The control unit 4 comprehensively controls each element of the liquid ejection device 1 by the control device executing a program stored in the storage device.

[0020] The transport mechanism 5 transports the medium S in the X-axis direction, and includes, for example, a transport roller 5a that is rotated by a transport motor that is driven under the control of the control unit 4.

[0021] The movement mechanism 6 is a mechanism for reciprocating the discharge unit 2 in the Y-axis direction, and includes a holder 6a, which is a so-called carriage that holds the discharge unit 2, and a conveyor belt 6b, which is an endless belt that is installed along the Y-axis direction. The control unit 4 controls the driving of a conveyor motor (not shown) to rotate the conveyor belt 6b, and moves the discharge unit 2 reciprocally in the Y-axis direction together with the holder 6a fixed to the conveyor belt 6b.

[0022] The discharge unit 2 performs a jetting operation of jetting ink supplied from the liquid storage unit 3 as ink droplets in the +Z direction from each of the multiple nozzles 21 (see FIG. 2) under the control of the control unit 4. This jetting operation by the discharge unit 2 is performed in parallel with the transport of the medium S by the transport mechanism 5 and the reciprocating movement of the discharge unit 2 by the movement mechanism 6, thereby applying ink to the medium S, or so-called printing.

[0023] 2 is a cross-sectional view of the discharge section 2 according to one embodiment of the present invention. Note that the directions of the discharge section 2 will be described based on the directions when the discharge section 2 is mounted on the liquid ejecting device 1, i.e., the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0024] As shown in the figure, the ejection section 2 of this embodiment includes a pressure chamber substrate 10, a communication plate 15, a nozzle plate 20 having a plurality of nozzles 21 formed therein, a protective substrate 30, a case member 40, a piezoelectric actuator 300, and a wiring member 110.

[0025] The pressure chamber substrate 10 is made of, for example, a silicon substrate. In the pressure chamber substrate 10, a plurality of pressure chambers 12 are arranged side by side along the X-axis direction. In this embodiment, the plurality of pressure chambers 12 are arranged side by side along the X-axis direction so as to be at the same position in the Y-axis direction. Two pressure chambers 12 adjacent to each other in the X-axis direction are separated by a partition wall (not shown). In this embodiment, two pressure chamber rows, in which the pressure chambers 12 are arranged side by side along the X-axis direction, are provided in the Y-axis direction.

[0026] A communication plate 15 and a nozzle plate 20 are stacked in this order on the surface of the pressure chamber substrate 10 facing the +Z direction. A vibration plate 50 and a piezoelectric actuator 300 are stacked in this order on the surface of the pressure chamber substrate 10 facing the -Z direction.

[0027] The communicating plate 15 is made of a plate-like member bonded to the surface of the pressure chamber substrate 10 facing the +Z direction. The communicating plate 15 is provided with nozzle communicating passages 16 that communicate between the pressure chambers 12 and the nozzles 21. The communicating plate 15 is also provided with a first common liquid chamber section 17 and a second common liquid chamber section 18 that constitute a common liquid chamber 100 that communicates with a plurality of pressure chambers 12. The first common liquid chamber section 17 is provided by penetrating the communicating plate 15 in the Z-axis direction. The second common liquid chamber section 18 is provided by opening onto the surface facing the +Z direction without penetrating the communicating plate 15 in the Z-axis direction. Furthermore, the communicating plate 15 is provided with supply communicating passages 19 that communicate with one end of the pressure chambers 12 in the Y-axis direction, independently for each pressure chamber 12. The supply communication passage 19 communicates the second common liquid chamber portion 18 with the pressure chamber 12, and supplies ink in the common liquid chamber 100 to the pressure chamber 12. As such a communication plate 15, a silicon substrate or the like can be used.

[0028] The nozzle plate 20 is bonded to the surface of the communication plate 15 facing the +Z direction. Nozzles 21 are formed in the nozzle plate 20, which communicate with each pressure chamber 12 via nozzle communication passages 16. In this embodiment, the multiple nozzles 21 are arranged in a row along the X-axis direction. Also, in this embodiment, two nozzle rows, in which the nozzles 21 are arranged side by side along the X-axis direction, are provided spaced apart in the Y-axis direction.

[0029] The material of the nozzle plate 20 is not particularly limited, and for example, a silicon substrate or the like can be used.

[0030] The vibration plate 50 has, for example, an elastic film 51 made of silicon oxide provided on the pressure chamber substrate 10 side, and an insulating film 52 made of zirconium oxide provided on the surface of the elastic film 51 facing the -Z direction.

[0031] The piezoelectric actuator 300 includes a first electrode 60 sequentially stacked in the -Z direction on the diaphragm 50, a piezoelectric layer 70 formed using a piezoelectric material, for example, a composite oxide with a perovskite structure represented by the general formula ABO3, and a second electrode 80. Such a piezoelectric actuator 300 is also referred to as a piezoelectric element, and refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. Furthermore, a portion of the piezoelectric layer 70 where piezoelectric strain occurs when a voltage is applied between the first electrode 60 and the second electrode 80 is referred to as an active portion 310. In contrast, a portion of the piezoelectric layer 70 where no piezoelectric strain occurs is referred to as an inactive portion. In other words, the active portion 310 refers to the portion of the piezoelectric layer 70 sandwiched between the first electrode 60 and the second electrode 80. In this embodiment, an active portion 310 is formed for each pressure chamber 12. In other words, the piezoelectric actuator 300 is formed with multiple active portions 310. The plurality of active portions 310 serve as driving elements that cause pressure changes in the ink within the pressure chambers 12. Generally, one of the electrodes of the active portions 310 is configured as an individual electrode that is independent for each active portion 310, and the other electrode is configured as a common electrode that is common to the plurality of active portions 310. In this embodiment, the first electrode 60 constitutes the individual electrode, and the second electrode 80 constitutes the common electrode.

[0032] Further, lead electrodes 91, which serve as lead wiring, are drawn out from each electrode of the piezoelectric actuator 300. A wiring member 110 made of a flexible substrate is connected to the end of each lead electrode 91 opposite to the end connected to the piezoelectric actuator 300. The wiring member 110 is equipped with a drive circuit 111 having a plurality of switching elements that select whether or not to supply a drive signal for driving each active portion 310 to each active portion 310, and a detection circuit 112 for detecting residual vibration. In other words, the wiring member 110 in this embodiment is a chip-on-film (COF). While the drive circuit 111 and the detection circuit 112 are shown as a single component in FIG. 2, the drive circuit 111 and the detection circuit 112 may be separate integrated circuits. The wiring member 110 does not necessarily have to include the drive circuit 111 and the detection circuit 112. In other words, the wiring member 110 may be an FFC (Flexible Flat Cable), an FPC (Flexible Printed Circuits), or the like.

[0033] A protective substrate 30 having approximately the same size as the pressure chamber substrate 10 is bonded to the surface of the pressure chamber substrate 10 facing the -Z direction. The protective substrate 30 has accommodation sections 31, which are spaces for protecting the piezoelectric actuators 300. The accommodation sections 31 are provided independently for each row of piezoelectric actuators 300 arranged side by side in the X-axis direction, with two accommodation sections 31 formed side by side in the Y-axis direction. The protective substrate 30 also has a through hole 32 penetrating in the Z-axis direction between the two accommodation sections 31 arranged side by side in the Y-axis direction. Ends of lead electrodes 91 drawn from each electrode of the piezoelectric actuators 300 extend so as to be exposed within the through hole 32, and the lead electrodes 91 and the wiring member 110 are electrically connected within the through hole 32. Such a protective substrate 30 may be made of, for example, a silicon substrate.

[0034] In addition, a case member 40 that defines a common liquid chamber 100 that communicates with the multiple pressure chambers 12 is fixed on the protective substrate 30. The case member 40 has substantially the same shape as the above-mentioned communicating plate 15 in a plan view, and is bonded to the protective substrate 30 as well as to the above-mentioned communicating plate 15.

[0035] The case member 40 has a recess 41 on the protective substrate 30 side that is deep enough to accommodate the pressure chamber substrate 10 and the protective substrate 30. This recess 41 has an opening area that is wider than the surface of the protective substrate 30 that is bonded to the pressure chamber substrate 10. Then, with the pressure chamber substrate 10 and the protective substrate 30 accommodated in the recess 41, the opening surface of the recess 41 on the nozzle plate 20 side is sealed by the communicating plate 15.

[0036] The case member 40 is also provided with a third common liquid chamber 42 that communicates with the first common liquid chamber 17 of the communication plate 15. The first common liquid chamber 17 and second common liquid chamber 18 provided in the communication plate 15 and the third common liquid chamber 42 provided in the case member 40 constitute a common liquid chamber 100 of this embodiment. A common liquid chamber 100 is provided for each row of pressure chambers 12, i.e., two common liquid chambers 100 in total. Each common liquid chamber 100 is provided continuously along the X-axis direction in which the pressure chambers 12 are arranged side by side, and the supply communication paths 19 that communicate each pressure chamber 12 with the common liquid chamber 100 are arranged side by side in the X-axis direction. The case member 40 is also provided with an inlet 44 that communicates with the common liquid chamber 100 and supplies ink to each common liquid chamber 100. The case member 40 is also provided with a connection port 43 that communicates with the through-hole 32 of the protection substrate 30 and through which the wiring member 110 is inserted. The case member 40 is made of a material such as a metal material or a resin material.

[0037] Furthermore, a compliance substrate 45 is provided on the surface of the communicating plate 15 on the +Z direction side where the first common liquid chamber portion 17 and the second common liquid chamber portion 18 open. This compliance substrate 45 seals the openings on the ejection surface side of the first common liquid chamber portion 17 and the second common liquid chamber portion 18. In this embodiment, such a compliance substrate 45 includes a sealing film 46 made of a flexible thin film, and a fixed substrate 47 made of a hard material such as metal. The area of ​​the fixed substrate 47 facing the common liquid chamber 100 is an opening 48 that is completely removed in the thickness direction, and therefore one side of the common liquid chamber 100 forms a compliance portion 49 that is a flexible portion sealed only by the flexible sealing film 46.

[0038] The ejection unit 2 takes in ink from the liquid storage unit 3 into the common liquid chamber 100 via the inlet 44, and after filling the interior from the common liquid chamber 100 to the nozzles 21 with ink, applies a voltage to each active section 310 corresponding to the pressure chambers 12 in accordance with an applied pulse from the drive circuit 111. This causes the active sections 310 and the vibration plate 50 to flex and deform, increasing the pressure of the ink in each pressure chamber 12 and causing the ink to be ejected from each nozzle 21 as an ink droplet.

[0039] 3 is a block diagram showing the electrical configuration of the liquid ejection device 1. The control unit 4 is an element that performs overall control of the liquid ejection device 1. The control unit 4 includes an external interface 211 (hereinafter referred to as the external I / F 211), a RAM 212 that temporarily stores various data, a ROM 213 that stores control programs and the like, a control processing unit 214 that includes a CPU and the like, an oscillation circuit 215 that generates a clock signal (CK), a drive signal generation circuit 216 that generates a drive signal to be supplied to the discharge unit 2, and an internal interface 217 (hereinafter referred to as the internal I / F 217).

[0040] The external I / F 211 is an interface for transmitting and receiving data to and from a host computer (not shown). Examples of data received by the control unit 4 from the host computer via the external I / F 211 include print data composed of character codes, graphic functions, image data, and the like. Examples of data transmitted by the control unit 4 via the external I / F 211 include a busy signal (BUSY) and an acknowledge signal (ACK). The RAM 212 functions as a receive buffer 212A, an intermediate buffer 212B, an output buffer 212C, and a work memory (not shown). The receive buffer 212A temporarily stores print data received by the external I / F 211, the intermediate buffer 212B stores intermediate code data converted by the control processing unit 214, and the output buffer 212C stores dot pattern data. The dot pattern data is composed of recording data (SI) obtained by decoding (translating) gradation data.

[0041] The drive signal generation circuit 216 generates a drive signal (COM) and transmits it to the ejection unit 2 via the internal I / F 217.

[0042] The ROM 213 stores font data, graphic functions, and the like, as well as control programs (control routines) for causing the control processing unit 214 to perform various data processing operations. The control processing unit 214 reads print data from the receive buffer 212A and converts the print data to generate intermediate code data, which it then stores in the intermediate buffer 212B. The control processing unit 214 also analyzes the intermediate code data read from the intermediate buffer 212B and converts the intermediate code data into pixel data by referencing the font data and graphic functions stored in the ROM 213. The control processing unit 214 then applies any necessary decoration processing and stores the converted pixel data in the output buffer 212C. The control program may be loaded from a recording medium, such as a floppy disk, CD-ROM, DVD-ROM, or USB memory, connected directly via the external I / F 211 or via the host computer. The control program may also be provided in the host computer as a printer driver.

[0043] Then, during printing, when the control processing unit 214 obtains recording data equivalent to one line of the discharge unit 2, it outputs this one line of recording data to the discharge unit 2 via the internal I / F 217. Furthermore, when one line of recording data is output from the output buffer 212C, the expanded intermediate code data is erased from the intermediate buffer 212B, and expansion processing is performed on the next intermediate code data.

[0044] The ejection unit 2 receives print data and a drive signal (COM) from the control unit 4, generates an individual drive signal for each active unit 310 from the drive signal (COM) in accordance with the print data, and supplies the individual drive signal to the active unit 310.

[0045] In this way, the discharge unit 2 discharges liquid from each nozzle 21 at a timing defined by the recording data SI and the like under the control of the control unit 4. The control unit 4 then controls the transport mechanism 5 to transport the medium S and the movement mechanism 6 to move the discharge unit 2 back and forth via the internal I / F 217 in parallel with the discharge operation by the discharge unit 2. Printing is performed on the medium S under such control of the control unit 4.

[0046] 4 is a block diagram showing the functional implementation units of the control unit 4. As shown in the figure, the control unit 4 includes a liquid information acquisition unit 200 and an adjustment unit 201.

[0047] The liquid information acquisition unit 200 detects information related to the residual vibration of the pressure chamber 12 via the detection circuit 112 as liquid information, and estimates the viscosity of the ink from the information related to the residual vibration. The information related to the residual vibration acquired by the liquid information acquisition unit 200 includes, for example, the period Tr of the residual vibration, the amplitude, or the damping state of the vibration. The liquid information acquisition unit 200 can acquire the residual vibration information by, for example, detecting, with the detection circuit 112, a residual vibration signal indicating fluctuations in the electromotive force generated in the active portion 310 due to the active portion 310 vibrating due to pressure vibrations remaining in the ink in the pressure chamber 12 after the active portion 310 is driven, and analyzing the residual vibration signal. The viscosity of the ink can be calculated from the information related to the residual vibration acquired in this manner, i.e., the period, amplitude, and damping state of the vibration. In other words, if the viscosity of the ink changes, the period Tr, amplitude, and vibration attenuation of the residual vibration of the electromotive voltage detected by the active section 310 will also change, so by determining in advance through experiments or the like the relationship between the period Tr, amplitude, and vibration attenuation state of the residual vibration and the viscosity of the ink, it is possible to estimate the viscosity of the ink from the residual vibration. The liquid information acquisition section 200 may calculate the viscosity of the ink from information related to the residual vibration detected by the detection circuit 112, or may directly use the residual vibration information as the effective viscosity.

[0048] The adjustment unit 201 calculates the viscosity of the ink based on the liquid information acquired by the liquid information acquisition unit 200 (in this embodiment, residual vibration information related to residual vibration), and controls the drive signal generation circuit 216 to generate an ejection pulse according to the calculated ink viscosity. Note that in this embodiment, the adjustment unit 201 controls the drive signal generation circuit 216 to generate an ejection pulse according to the ink viscosity so that there is no variation in the ejection amount ejected from the nozzles 21 even if the ink viscosity changes.

[0049] Here, the ejection pulses DP1 to DP4, which are examples of the ejection pulses included in the drive signal COM that the adjustment unit 201 causes the drive signal generation circuit 216 to generate, will be described with reference to Fig. 5 to Fig. 8. Fig. 5 to Fig. 8 are waveform diagrams showing the ejection pulses DP1 to DP4, which are examples of the ejection pulses.

[0050] 5, the drive signal COM is repeatedly generated by the drive signal generation circuit 216 for each drive period T. The drive period T is also called the recording period T, and corresponds to one pixel of an image to be printed on the medium S.

[0051] In this embodiment, the drive signal COM is supplied to the first electrode 60, which is an individual electrode, with the second electrode 80, which is a common electrode of the active section 310, serving as a reference potential. That is, the voltage applied to the second electrode 80 by the drive signal COM is expressed as a potential with the reference potential as a reference. The drive signal COM is a drive potential in a broad sense.

[0052] The drive signal COM shown in FIG. 5 is a signal having one ejection pulse DP1 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0053] The ejection pulse DP1 has an expansion element a1, an expansion maintaining element a2, a contraction element a3, a contraction maintaining element a4, and a re-expansion element a5, which are arranged in this order in time series.

[0054] The expansion element a1 changes the potential from intermediate potential Vm1 to potential V1, expanding the volume of the pressure chamber 12 from the reference volume. This expansion element a1 draws the ink liquid surface in the nozzle 21, the so-called meniscus, toward the pressure chamber 12, and liquid is supplied to the pressure chamber 12 from the common liquid chamber 100 side. The potential change width of the expansion element a1 from intermediate potential Vm1 to potential V1 is called the potential change width Vc1. The expansion maintenance element a2 maintains potential V1 for a certain period of time. While the expansion maintenance element a2 is being supplied, pressure fluctuations occur in the ink in the pressure chamber 12 due to the natural vibration period Tc. The period of pressure vibration of the ink in the pressure chamber 12, the so-called natural vibration period Tc, can generally be expressed by the following equation (1):

[0055]

number

[0056] In the above formula (1), Mn is the inertance of the nozzle 21 (the value obtained by dividing the mass of ink per unit cross-sectional area by the cross-sectional area), Ms is the inertance of the supply communication path 19, C is the compliance obtained by adding Cc and Ci, Cc is the compliance of the pressure chamber 12 (indicating the volume change per unit pressure, or the degree of softness), and Ci is the compliance of the liquid (Ci = volume V / [density ρ × speed of sound cb]). Also, ζ is the damping ratio, which is expressed by formula (2).

[0057]

number

[0058] In the above formula (2), R is the resistance proportional to the viscosity, and M is the inertance, which is expressed by the following formula (3).

[0059]

number

[0060] The contraction element a3 changes its potential from potential V1 to potential V2, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. The potential change width of the contraction element a3 from potential V1 to potential V2 is referred to as potential change width Vh1. Furthermore, the potential V1, which is the terminal potential of the expansion element a1, is equal to the potential V1, which is the starting potential of the contraction element a3. In this embodiment, the potential change width Vc1 is 50% of the potential change width Vh1.

[0061] The period t1 from the start of the expansion element a1 to the end of the expansion maintenance element a2, i.e., the start of the contraction element a3, is set appropriately, for example, to 1 / 2 the natural vibration period Tc, specifically, to be 0.25 to 0.75 times the natural vibration period Tc. The vibrations within the pressure chamber 12 caused by the expansion element a1 to expand the pressure chamber 12 remain as residual vibrations (residual vibrations of the meniscus of the nozzle 21) due to the natural vibration period Tc even after the expansion maintenance element a2, significantly affecting the contraction of the pressure chamber 12 caused by the contraction element a3. For example, if the contraction element a3 is initiated while the meniscus is vibrating in a direction that protrudes away from the pressure chamber 12, the ejection volume, which is the weight of the liquid, tends to increase. Conversely, if the contraction element a3 is initiated while the meniscus is vibrating in a direction that draws the meniscus toward the pressure chamber 12, the ejection volume tends to decrease. By setting the period t1 to be 0.25 or more and 0.75 or less times the natural vibration period Tc, the contraction element a3 can be started while the meniscus is vibrating in the direction protruding in the opposite direction from the pressure chamber 12, thereby increasing the amount of ink ejected.

[0062] The contraction maintaining element a4 maintains the potential V2, which is the potential at the end point of the contraction element a3, for a certain period of time. While the contraction maintaining element a4 is being supplied to the active portion 310, pressure vibrations occur in the liquid within the pressure chamber 12 with the natural vibration period Tc.

[0063] The re-expansion element a5 changes the potential from the potential V2 to the intermediate potential Vm1, expanding the volume of the pressure chamber 12. This re-expansion element a5 weakens the pressure vibration of the liquid in the pressure chamber 12, that is, the residual vibration of the meniscus.

[0064] The period t2 from the start of the contraction element a3 to the end of the contraction maintenance element a4, i.e., the start of the re-expansion element a5, is appropriately set, for example, to be near the natural vibration period Tc, specifically to be 0.75 to 1.25 times the natural vibration period Tc. In other words, as described above, by starting the re-expansion element a5 while the meniscus is vibrating in a direction protruding away from the pressure chamber 12, the residual vibration of the meniscus can be weakened and the vibration of the meniscus can be damped relatively quickly.

[0065] The elements a1 to a5 and periods t1 and t2 of the ejection pulse DP1 of the drive signal COM are set in advance through experiments, etc., so that stable printing can be performed in the initial state (at the time of shipment from the factory). That is, since the viscosity and surface tension of ink vary depending on the ink, the ejection pulse DP1 is set so that the ejection amount, flight speed, shape, etc. of the ink are optimized for the viscosity of a standard ink, for example, 4 m·Pas in this embodiment, and the surface tension. Note that the standard liquid is, for example, ink managed and manufactured by the manufacturer of the liquid ejection device 1, whose characteristics are understood by the manufacturer. As a result, it is possible to set the elements a1 to a5 and period t1 of the ejection pulse DP1 of the drive signal COM appropriately.

[0066] The drive signal COM shown in FIG. 6 is a signal having one ejection pulse DP2 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0067] The ejection pulse DP2 is a driving waveform in which the intermediate potential Vm1 of the ejection pulse DP1 is changed to an intermediate potential Vm2 higher than the intermediate potential Vm1.

[0068] The ejection pulse DP2 has an expansion element b1, an expansion maintaining element b2, a contraction element b3, a contraction maintaining element b4, and a re-expansion element b5, which are arranged in this order in time series.

[0069] The expansion element b1 changes its potential from the intermediate potential Vm2 to the potential V3, thereby expanding the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element b1 from the intermediate potential Vm2 to the potential V3 is referred to as the potential change width Vc2. In this embodiment, the potential V3 is the same potential as the potential V1 of the ejection pulse DP1.

[0070] The expansion maintaining element b2 maintains the potential V3 for a certain period of time. While the expansion maintaining element b2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0071] The contraction element b3 changes its potential from potential V3 to potential V4, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. In this embodiment, the potential V4 is the same as the potential V2 of the ejection pulse DP1. The potential change width of the contraction element b3 from potential V3 to potential V4 is referred to as the potential change width Vh2. In other words, the potential change width Vh2 is the same as the potential change width Vh1 of the ejection pulse DP1. The potential V3, which is the terminal potential of the expansion element b1, is equal to the potential V3, which is the starting potential of the contraction element b3. In this embodiment, the potential change width Vc2 is 80% of the potential change width Vh2.

[0072] The period t3 from the start of the expansion component b1 to the end of the expansion maintenance component b2, i.e., the start of the contraction component b3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the period t1 of the ejection pulse DP1. In other words, the period t3 is the same as the period t1 of the ejection pulse DP1. This allows the ejection amount ejected from the nozzle 21 to be increased.

[0073] The contraction maintenance element b4 maintains the potential V4, which is the potential at the end point of the contraction element b3, for a certain period of time.

[0074] The re-expansion element b5 changes the potential from the potential V4 to the intermediate potential Vm2, expanding the volume of the pressure chamber 12. This re-expansion element b5 weakens the pressure vibration of the liquid in the pressure chamber 12, that is, the residual vibration of the meniscus.

[0075] The period t4 from the start of the contraction element b3 to the end of the contraction maintenance element b4, i.e., the start of the re-expansion element b5, is appropriately set to be 0.75 to 1.25 times the natural vibration period Tc, similar to the period t2 of the ejection pulse DP1. In other words, the period t4 is the same as the period t2 of the ejection pulse DP1.

[0076] Such an ejection pulse DP2 is used when the viscosity of the ink is higher than the viscosity of the reference ink, for example, when the viscosity is 8 m·Pas.

[0077] The drive signal COM shown in FIG. 7 is a signal having one ejection pulse DP3 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0078] The ejection pulse DP3 is a drive waveform in which the intermediate potential Vm1 of the ejection pulse DP1 is changed to an intermediate potential Vm3 that is higher than the intermediate potentials Vm1 and Vm2. Note that the intermediate potential Vm3 is a drive waveform in which the potential is the same as the potential V2 of the ejection pulse DP1.

[0079] The ejection pulse DP3 has an expansion element c1, an expansion maintaining element c2, and a contraction element c3, which are successively arranged in this order in time series.

[0080] The expansion element c1 changes its potential from the intermediate potential Vm3 to the potential V5, thereby expanding the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element c1 from the intermediate potential Vm3 to the potential V5 is referred to as the potential change width Vc3. In this embodiment, the potential V5 is the same potential as the potential V1 of the ejection pulse DP1.

[0081] The expansion maintaining element c2 maintains the potential V5 for a certain period of time. While the expansion maintaining element c2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0082] The contraction element c3 changes its potential from potential V5 to intermediate potential Vm3, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. In this embodiment, the intermediate potential Vm3 is the same potential as the potential V2 of the ejection pulse DP1. The potential change width of the contraction element c3 from the potential V5 to the intermediate potential Vm3 is referred to as the potential change width Vh3. In other words, the potential change width Vh3 is the same as the potential change width Vh1 of the ejection pulse DP1. The potential V5, which is the terminal potential of the expansion element c1, is equal to the potential V5, which is the starting potential of the contraction element c3. In this embodiment, the potential change width Vc3 is 100% of the potential change width Vh3.

[0083] The period t5 from the start of the expansion component c1 to the end of the expansion maintenance component c2, i.e., the start of the contraction component c3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the period t1 of the ejection pulse DP1. In other words, the period t5 is the same as the period t1 of the ejection pulse DP1. This allows the ejection amount ejected from the nozzle 21 to be increased.

[0084] Such an ejection pulse DP3 is used when the viscosity of the ink is higher than the viscosity of the reference ink and the viscosity of the ink for which the ejection pulse DP2 is used, for example, when the viscosity is 9.2 m·Pas.

[0085] The drive signal COM shown in FIG. 8 is a signal having one ejection pulse DP4 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0086] The ejection pulse DP4 is a driving waveform in which the intermediate potential Vm1 of the ejection pulse DP1 is changed to an intermediate potential Vm4 which is higher than the intermediate potentials Vm1 to Vm3.

[0087] The ejection pulse DP4 has an expansion element d1, an expansion maintaining element d2, a contraction element d3, a contraction maintaining element d4, and a re-contraction element d5, which are arranged in this order in time series.

[0088] The expansion element d1 changes its potential from the intermediate potential Vm4 to the potential V6, thereby expanding the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element d1 from the intermediate potential Vm4 to the potential V6 is referred to as the potential change width Vc4. In this embodiment, the potential V6 is the same potential as the potential V1 of the ejection pulse DP1.

[0089] The expansion maintaining element d2 maintains the potential V6 for a certain period of time. While the expansion maintaining element d2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0090] The contraction element d3 changes potential from potential V6 to potential V7, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. In this embodiment, potential V7 is the same potential as potential V2 of the ejection pulse DP1. The potential change width of the contraction element d3 from potential V6 to potential V7 is referred to as potential change width Vh4. In other words, the potential change width Vh4 is the same as the potential change width Vh1 of the ejection pulse DP1. The potential V6, which is the terminal potential of the expansion element d1, is equal to the potential V6, which is the starting potential of the contraction element d3. In this embodiment, the potential change width Vc4 is 150% of the potential change width Vh4. Hereinafter, when the potential change widths Vc1 to Vc4 of the expansion elements a1 to d1 are not distinguished, they will be referred to as potential change width Vc, and when the potential change widths Vh1 to Vh4 of the contraction elements a3 to d3 are not distinguished, they will be referred to as potential change width Vh.

[0091] The period t6 from the start of the expansion element d1 to the end of the expansion maintenance element d2, i.e., the start of the contraction element d3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the period t1 of the ejection pulse DP1. In other words, the period t6 is the same as the period t1 of the ejection pulse DP1. This allows the ejection amount ejected from the nozzle 21 to be increased.

[0092] The contraction maintenance element d4 maintains the potential V7, which is the potential at the end point of the contraction element d3, for a certain period of time.

[0093] The re-contraction element d5 changes the potential from V7 to an intermediate potential Vm4, thereby contracting the volume of the pressure chamber 12 to the reference volume. This re-contraction element d5 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. Specifically, the period t7 from the start of the contraction element d3 to the end of the contraction maintenance element d4, i.e., the start of the re-contraction element d5, is appropriately set, for example, to 1 / 2 the natural vibration period Tc, specifically to 0.25 to 0.75 times the natural vibration period Tc. By setting the period t7 to 0.25 to 0.75 times the natural vibration period Tc, the re-contraction element d5 can be started while the meniscus is vibrating in a direction drawn toward the pressure chamber 12, thereby weakening the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus.

[0094] Such an ejection pulse DP4 is used when the viscosity of the ink is higher than the viscosity of the ink that is the reference for use with the ejection pulse DP1, the viscosity of the ink that is used with the ejection pulse DP2, and the viscosity of the ink that is used with the ejection pulse DP3, for example, when the viscosity is 12 m·Pas.

[0095] 9 and 10 are graphs showing the relationship between the viscosity of the ink and the ratio of the potential change width Vc to the potential change width Vh at which the amount of ink ejected from the nozzle 21 becomes constant.

[0096] As shown in Figure 9, by increasing the ratio of the potential change width Vc to the potential change width Vh to a ratio greater than 100%, for example, to 200%, it is possible to eject ink with the same ejection volume even if the ink viscosity is higher than 9.2 m·Pas.

[0097] In contrast, as shown in Figure 10, if the ratio of the potential change width Vc to the potential change width Vh is limited to 100%, the upper limit of the viscosity of ink that can be ejected with the same ejection volume is 9.2 m·Pas, and ink with a higher viscosity than this cannot be ejected with the same ejection volume.

[0098] In other words, in this embodiment, by changing the intermediate potential Vm so that the potential change width Vc is at a ratio up to 100% of the potential change width Vh, as well as so that the potential change width Vc is at a ratio higher than 100% of the potential change width Vh, it is possible to suppress variations in the amount of liquid ejected from the nozzle 21, even in the case of ink with a relatively high viscosity.

[0099] A two-dimensional table, such as that shown in the graph in FIG. 9, may be prepared in advance, associating the ink viscosity with the ratio of the potential change width Vc to the potential change width Vh. The adjustment unit 201 may adjust the ratio of the potential change width Vc to the potential change width Vh based on this two-dimensional table. The two-dimensional table may associate the ink viscosity with ejection pulses of a plurality of waveforms, such as the ejection pulses DP1 to DP4, and the adjustment unit 201 may select the ejection pulses DP1 to DP4, etc., according to the ink viscosity. Such a two-dimensional table may be stored in a memory element, such as the ROM 213, provided in the control unit 4. Of course, the memory element storing the two-dimensional table is not limited to the memory element provided in the control unit 4, but may also be another memory element provided outside the control unit 4. The other memory element may be a memory element built into the ejection unit 2, such as a memory element built into the drive circuit 111 or the detection circuit 112. If the ejection unit 2 is equipped with a memory element other than the drive circuit 111 or the detection circuit 112, the two-dimensional table may be stored therein. Of course, it may be a storage element provided outside the ejection unit 2 that stores the two-dimensional table.

[0100] In this way, the adjustment unit 201 selects ejection pulses DP1 to DP4, etc., with an adjusted ratio of the potential change width Vc to the potential change width Vh based on information related to the viscosity of the ink acquired by the liquid information acquisition unit 200, and drives the active unit 310 with the ejection pulses DP1 to DP4 according to the ink viscosity, thereby suppressing variations in the ejection amount ejected from the nozzle 21 even when the viscosity of the ink changes. Incidentally, the flight speed of the ink ejected from the nozzle 21 also exhibits the same tendency as the ejection amount with respect to changes in the viscosity of the ink. Therefore, by selecting ejection pulses DP1 to DP4 according to the viscosity of the ink and driving the active unit 310 with the selected ejection pulses DP1 to DP4, it is possible to suppress variations in the flight speed of the ink ejected from the nozzle 21 even when the viscosity of the ink changes. Therefore, it is possible to suppress deviations in the landing position of the ink on the medium S due to variations in the flight speed of the ink. In other words, the adjustment unit 201 selects ejection pulses DP1 to DP4 according to the viscosity of the ink and drives the active unit 310 with the selected ejection pulses DP1 to DP4, thereby suppressing variations in ejection characteristics such as the ejection amount and flight speed even if the viscosity of the ink changes.

[0101] In this embodiment, the potential change widths Vh1 to Vh4 of the contraction elements a3 to d3 of the ejection pulses DP1 to DP4 are equal, and the ratio of the potential change widths Vc1 to Vc4 of the expansion elements a1 to d1 to the potential change width Vh is changed to suppress variations in the ink ejection volume. By making the potential change widths Vh1 to Vh4 equal, the ink retraction after ejection is reduced, making it less likely for air bubbles to be trapped in the nozzle 21 after ink ejection. In other words, when the ink viscosity is high, attempting to suppress variations in the ejection volume by significantly increasing the contraction element Vh may easily trap air bubbles after ejection, which may cause ejection defects or the like. In this embodiment, even when the ink viscosity is high, variations in the ejection volume can be suppressed without increasing the contraction element Vh. This makes it less likely for air bubbles to be trapped in the nozzle 21 after ink ejection, suppressing ejection defects caused by trapped air bubbles and improving ejection stability. Furthermore, by making the potential change widths Vh1 to Vh4 of the ejection pulses DP1 to DP4 equal, there is no need to make complex changes to the waveform shapes of the ejection pulses DP1 to DP4, and control of the waveform shapes is easy.

[0102] Of course, the potential change widths Vh1 to Vh4 may each be changed according to the viscosity of the ink. For example, when the viscosity of the ink is high, the potential change width Vh may be made relatively large, and when the viscosity of the ink is low, the potential change width Vh may be made relatively small. In other words, the potential change width Vh4 of the contraction element d3 of the ejection pulse DP4 may be adjusted to be larger than the potential change width Vh1 of the contraction element a3 of the ejection pulse DP1.

[0103] In this embodiment, an ink viscosity of 9.2 m·Pas is an example of a "first viscosity," liquid information including this first viscosity is an example of "first information," and the ejection pulse DP3 is an example of a "first ejection pulse." Ink viscosities of 4 m·Pas, 8 m·Pas, and 12 m·Pas are examples of a "second viscosity," liquid information including this second viscosity is an example of "second information," and the ejection pulses DP1, DP2, and DP4 are examples of "second ejection pulses." When the above-mentioned "second viscosity" is lower than the "first viscosity," that is, when the "second viscosity" is 4 m·Pas or 8 m·Pas, the "second ejection pulse" becomes the ejection pulse DP1 or DP2. When the "second viscosity" is higher than the "first viscosity," that is, when the "second viscosity" is 12 m·Pas, the "second ejection pulse" becomes the ejection pulse DP4.

[0104] In addition, in this embodiment, an ink viscosity of 4 m·Pas or 8 m·Pas is an example of a "third viscosity," liquid information including this third viscosity is an example of "third information," and ejection pulses DP1 and DP2 are an example of a "third ejection pulse." In addition, an ink viscosity of 12 m·Pas is an example of a "fourth viscosity," liquid information including this fourth viscosity is an example of "fourth information," and ejection pulse DP4 is an example of a "fourth ejection pulse." In other words, the ejection pulse DP3 of this embodiment may not be present.

[0105] (Embodiment 2) 11 to 14 are waveform diagrams of the ejection pulses DP10 to DP13 according to embodiment 2. Note that the same members as those in the above-described embodiment are given the same reference numerals, and redundant explanations will be omitted.

[0106] The drive signal COM shown in FIG. 11 is a signal having one ejection pulse DP10 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0107] The ejection pulse DP10 has an expansion element e1, an expansion maintaining element e2, a contraction element e3, a contraction maintaining element e4, and a re-expansion element e5, which are arranged in this order in time series.

[0108] The expansion element e1 changes potential from intermediate potential Vm10 to potential V10 to expand the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element e1 from intermediate potential Vm10 to potential V10 is referred to as potential change width Vc10.

[0109] The expansion maintaining element e2 maintains the potential V10 for a certain period of time. While the expansion maintaining element e2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0110] The contraction element e3 changes its potential from potential V10 to potential V11, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. The potential change width of the contraction element e3 from potential V10 to potential V11 is referred to as potential change width Vh10. The potential V10, which is the terminal potential of the expansion element e1, is equal to the potential V10, which is the starting potential of the contraction element e3. In this embodiment, the potential change width Vc10 is 50% of the potential change width Vh10.

[0111] The period from the start point of the expansion element e1 to the end point of the expansion maintenance element e2, i.e., the start point of the contraction element e3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the period t1 of the ejection pulse DP1 in the above-described embodiment 1. This allows the ejection amount ejected from the nozzle 21 to be increased.

[0112] The contraction maintaining element e4 maintains the potential V11, which is the potential at the end point of the contraction element e3, for a certain period of time. While the contraction maintaining element e4 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0113] The re-expansion element e5 changes the potential from potential V11 to intermediate potential Vm10, expanding the volume of the pressure chamber 12. This re-expansion element e5 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In this embodiment, the potential change width of the re-expansion element e5 from potential V11 to intermediate potential Vm10 is referred to as potential change width Vs1.

[0114] The period t10 from the start of the contraction element e3 to the end of the contraction maintenance element e4, i.e., the start of the re-expansion element e5, is appropriately set to be 0.75 to 1.25 times the natural vibration period Tc, similar to the period t2 of the ejection pulse DP1 in embodiment 1. By specifying the period t10 in this manner, the residual vibration of the meniscus can be efficiently weakened by the re-expansion element e5.

[0115] Such an ejection pulse DP10 is used when the viscosity of the ink is a reference viscosity, for example, 4 m·Pas.

[0116] The drive signal COM shown in FIG. 12 is a signal having one ejection pulse DP11 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0117] The ejection pulse DP11 is a drive waveform in which the intermediate potential Vm10 of the ejection pulse DP10 is changed to an intermediate potential Vm11 higher than the intermediate potential Vm10.

[0118] The ejection pulse DP11 has an expansion element f1, an expansion maintaining element f2, a contraction element f3, a contraction maintaining element f4, a re-expansion element f5, a re-expansion maintaining element f6, and a re-contraction element f7, which are arranged in this order in time series.

[0119] The expansion element f1 changes the potential from an intermediate potential Vm11 to a potential V12, thereby expanding the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element f1 from the intermediate potential Vm11 to the potential V12 is referred to as the potential change width Vc11. In this embodiment, the potential V12 is the same potential as the potential V10 of the ejection pulse DP10.

[0120] The expansion maintaining element f2 maintains the potential V12 for a certain period of time. While the expansion maintaining element f2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0121] The contraction element f3 changes its potential from potential V12 to potential V13, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. In this embodiment, the potential V13 is the same as the potential V11 of the ejection pulse DP10. The potential change width of the contraction element f3 from potential V12 to potential V13 is referred to as the potential change width Vh11. In other words, the potential change width Vh11 is the same as the potential change width Vh10 of the ejection pulse DP10. The potential V12, which is the terminal potential of the expansion element f1, is equal to the potential V12, which is the starting potential of the contraction element f3. In this embodiment, the potential change width Vc11 is 80% of the potential change width Vh11.

[0122] The period from the start of the expansion element f1 to the end of the expansion maintenance element f2, i.e., the start of the contraction element f3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the ejection pulse DP10. In other words, this period is the same as the period of the ejection pulse DP10. By specifying the period in this way, the ejection amount ejected from the nozzle 21 can be increased.

[0123] The contraction maintaining element f4 maintains the potential V13, which is the potential at the end point of the contraction element f3, for a certain period of time. While the contraction maintaining element f4 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0124] The re-expansion element f5 changes the potential from V13 to V14, expanding the volume of the pressure chamber 12. This re-expansion element f5 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In this embodiment, the potential change width from V13 to V14 is referred to as the potential change width Vs2. The potential V14 of the re-expansion element f5 is the same potential as the midpoint potential Vm10 of the ejection pulse DP10. Therefore, the potential change width Vs2 of the ejection pulse DP11 is the same as the potential change width Vs1 of the ejection pulse DP10. Therefore, even in ejection pulses DP10 and DP11 with different ratios of the potential change width Vc of the expansion element to the potential change width Vh of the contraction element, the re-expansion elements e5 and f5 with the same potential change widths Vs1 and Vs2 can damp the meniscus of the nozzle 21, thereby enabling the vibration in the nozzle 21 to be damped in the same way after ejecting ink. Therefore, ejection stability can be improved when ink is ejected continuously.

[0125] The period t11 from the start of the contraction element f3 to the end of the contraction maintenance element f4, i.e., the start of the re-expansion element f5, is appropriately set to be 0.75 to 1.25 times the natural vibration period Tc, similar to the period t10 of the ejection pulse DP10. In other words, the period t11 is the same as the period t10 of the ejection pulse DP10. By specifying the period t11 in this manner, the re-expansion element f5 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0126] The re-expansion maintaining element f6 maintains the potential V14, which is the potential at the end point of the re-expansion element f5, for a certain period of time. While the re-expansion maintaining element f6 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0127] The re-contraction element f7 changes the potential from V14 to an intermediate potential Vm11, thereby contracting the volume of the pressure chamber 12. This re-contraction element f7 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In other words, the period t12 from the start of the contraction element f3 to the end of the re-expansion maintenance element f6, i.e., the start of the re-contraction element f7, is appropriately set to be 1.25 to 1.75 times the natural vibration period Tc. By specifying the period t12 in this manner, the re-contraction element f7 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0128] Such an ejection pulse DP11 is used when the viscosity of the ink is higher than the viscosity of the reference ink, for example, 8 m·Pas.

[0129] The drive signal COM shown in FIG. 13 is a signal having one ejection pulse DP12 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0130] The ejection pulse DP12 is a drive waveform in which the intermediate potential Vm11 of the ejection pulse DP11 is changed to an intermediate potential Vm12 higher than the intermediate potential Vm11.

[0131] The ejection pulse DP12 has an expansion element g1, an expansion maintaining element g2, a contraction element g3, a contraction maintaining element g4, a re-expansion element g5, a re-expansion maintaining element g6, and a re-contraction element g7, which are arranged in this order in time series.

[0132] The expansion element g1 changes its potential from an intermediate potential Vm12 to a potential V15, thereby expanding the volume of the pressure chamber 12 from its reference volume. The potential change width of the expansion element g1 from the intermediate potential Vm12 to the potential V15 is referred to as the potential change width Vc12. In this embodiment, the intermediate potential Vm12 is the same potential as the potential V11 of the ejection pulse DP10, and the potential V15 is the same potential as the potential V10 of the ejection pulse DP10.

[0133] The expansion maintaining element g2 maintains the potential V15 for a certain period of time. While the expansion maintaining element g2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0134] The contraction element g3 changes its potential from potential V15 to intermediate potential Vm12, contracting the volume of the pressure chamber 12 and ejecting ink from the nozzle 21. In this embodiment, the intermediate potential Vm12 is the same as the potential V11 of the ejection pulse DP10, so the potential change width Vh12 of the contraction element g3 from the potential V15 to the intermediate potential Vm12 is the same as the potential change width Vh10 of the ejection pulse DP10. Furthermore, the potential V15, which is the terminal potential of the expansion element g1, is equal to the potential V15, which is the starting potential of the contraction element g3. In this embodiment, the potential change width Vc12 is 100% of the potential change width Vh12.

[0135] The period from the start of the expansion element g1 to the end of the expansion maintenance element g2, i.e., the start of the contraction element g3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the ejection pulse DP10. In other words, this period is the same as the period of the ejection pulse DP10. By specifying the period in this way, the ejection amount ejected from the nozzle 21 can be increased.

[0136] The contraction maintaining element g4 maintains the intermediate potential Vm12, which is the potential at the end point of the contraction element g3, for a certain period of time. While the contraction maintaining element g4 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0137] The re-expansion element g5 changes the potential from the intermediate potential Vm12 to the potential V16, thereby expanding the volume of the pressure chamber 12. This re-expansion element g5 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In this embodiment, the potential change width from the intermediate potential Vm12 to the potential V16 is referred to as the potential change width Vs3. The potential V16 of the re-expansion element g5 is the same potential as the intermediate potential Vm10 of the ejection pulse DP10. Therefore, the potential change width Vs3 of the ejection pulse DP12 is the same as the potential change width Vs1 of the ejection pulse DP10. Therefore, even in the ejection pulses DP10, DP11, and DP12 that have different ratios of the potential change width Vc of the expansion element to the potential change width Vh of the contraction element, the vibration of the meniscus of the nozzle 21 can be suppressed with the re-expansion elements e5, f5, and g5 of the same potential change widths Vs1, Vs2, and Vs3, so that the damping of the vibration inside the nozzle 21 after ejecting ink can be performed in the same way. Therefore, ejection stability can be improved when ejecting ink continuously.

[0138] The period t13 from the start of the contraction element g3 to the end of the contraction maintenance element g4, i.e., the start of the re-expansion element g5, is appropriately set to be 0.75 to 1.25 times the natural vibration period Tc, similar to the period t10 of the ejection pulse DP10. In other words, the period t13 is the same as the period t10 of the ejection pulse DP10. By specifying the period t13 in this manner, the re-expansion element g5 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0139] The re-expansion maintaining element g6 maintains the potential V16, which is the potential at the end point of the re-expansion element g5, for a certain period of time. While the re-expansion maintaining element g6 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0140] The re-contraction element g7 changes the potential from V16 to an intermediate potential Vm12, thereby contracting the volume of the pressure chamber 12. This re-contraction element g7 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In other words, the period t14 from the start of the contraction element g3 to the end of the re-expansion maintenance element g6, i.e., the start of the re-contraction element g7, is appropriately set to be 1.25 to 1.75 times the natural vibration period Tc, similar to the period t12 of the ejection pulse DP11. By specifying the period t14 in this manner, the re-contraction element g7 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0141] Such an ejection pulse DP12 is used when the viscosity of the ink is higher than the viscosity of the reference ink and the viscosity of the ink for which the ejection pulse DP11 is used, for example, when the viscosity is 9.2 m·Pas.

[0142] The drive signal COM shown in FIG. 14 is a signal having one ejection pulse DP13 in one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0143] The ejection pulse DP13 is a drive waveform in which the intermediate potential Vm12 of the ejection pulse DP12 is changed to an intermediate potential Vm13 higher than the intermediate potential Vm12.

[0144] The ejection pulse DP13 has an expansion element h1, an expansion maintaining element h2, a contraction element h3, a contraction maintaining element h4, a re-expansion element h5, a re-expansion maintaining element h6, and a re-contraction element h7, which are arranged in this order in time series.

[0145] The expansion element h1 changes its potential from an intermediate potential Vm13 to a potential V17, thereby expanding the volume of the pressure chamber 12 from the reference volume. The potential change width of the expansion element h1 from the intermediate potential Vm13 to the potential V17 is referred to as the potential change width Vc13. In this embodiment, the potential V17 is the same potential as the potential V10 of the ejection pulse DP10.

[0146] The expansion maintaining element h2 maintains the potential V17 for a certain period of time. While the expansion maintaining element h2 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0147] The contraction element h3 changes potential from potential V17 to potential V18 to contract the volume of the pressure chamber 12 and eject ink from the nozzle 21. In this embodiment, the potential V18 is the same as the potential V11 of the ejection pulse DP10, so the potential change width Vh13 of the contraction element h3 from potential V17 to potential V18 is the same as the potential change width Vh10 of the ejection pulse DP10. Furthermore, the potential V17, which is the terminal potential of the expansion element h1, is equal to the potential V17, which is the starting potential of the contraction element h3. In this embodiment, the potential change width Vh13 is 150% of the potential change width Vh13.

[0148] The period from the start of the expansion element h1 to the end of the expansion maintenance element h2, i.e., the start of the contraction element h3, is appropriately set to be 0.25 to 0.75 times the natural vibration period Tc, similar to the ejection pulse DP10. In other words, this period is the same as the period of the ejection pulse DP10. By specifying the period in this way, the ejection amount ejected from the nozzle 21 can be increased.

[0149] The contraction maintaining element h4 maintains the potential V18, which is the potential at the end point of the contraction element h3, for a certain period of time. While the contraction maintaining element h4 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0150] The re-expansion element h5 changes the potential from potential V18 to potential V19, expanding the volume of the pressure chamber 12. This re-expansion element h5 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In this embodiment, the potential change width from potential V18 to potential V19 is referred to as potential change width Vs4. The potential V19 of the re-expansion element h5 is the same potential as the intermediate potential Vm10 of the ejection pulse DP10. Therefore, the potential change width Vs4 of the ejection pulse DP13 is the same as the potential change width Vs1 of the ejection pulse DP10. Therefore, even in the ejection pulses DP10, DP11, DP12, and DP13 in which the ratio of the potential change width Vc of the expansion element to the potential change width Vh of the contraction element is different, the vibration of the meniscus of the nozzle 21 can be suppressed with the re-expansion elements e5, f5, g5, and h5 of the same potential change widths Vs1, Vs2, Vs3, and Vs4, and therefore the damping of the vibration inside the nozzle 21 after ejecting ink can be performed in the same way. Therefore, the ejection stability can be improved when ejecting ink continuously.

[0151] The period t15 from the start of the contraction element h3 to the end of the contraction maintenance element h4, i.e., the start of the re-expansion element h5, is appropriately set to be 0.75 to 1.25 times the natural vibration period Tc, similar to the period t10 of the ejection pulse DP10. In other words, the period t15 is the same as the period t10 of the ejection pulse DP10. By specifying the period t15 in this manner, the re-expansion element h5 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0152] The re-expansion maintaining element h6 maintains the potential V19, which is the potential at the end point of the re-expansion element h5, for a certain period of time. While the re-expansion maintaining element h6 is being supplied, pressure fluctuations occur in the ink inside the pressure chamber 12 due to the natural vibration period Tc.

[0153] The re-contraction element h7 changes the potential from potential V19 to intermediate potential Vm13, thereby contracting the volume of the pressure chamber 12. This re-contraction element h7 weakens the pressure vibration of the liquid in the pressure chamber 12, i.e., the residual vibration of the meniscus. In other words, the period t16 from the start of the contraction element h3 to the end of the re-expansion maintenance element h6, i.e., the start of the re-contraction element h7, is appropriately set to be 1.25 to 1.75 times the natural vibration period Tc, similar to the period t12 of the ejection pulse DP11. By specifying the period t16 in this manner, the re-contraction element h7 efficiently weakens the residual vibration of the meniscus in the nozzle 21.

[0154] Such an ejection pulse DP13 is used when the viscosity of the ink is higher than the viscosity of the reference ink, the viscosity of the ink for which the ejection pulse DP11 is used, and the viscosity of the ink for which the ejection pulse DP12 is used, for example, 12 m·Pas.

[0155] The adjustment unit 201 selects ejection pulses DP10 to DP13, etc., for which the ratio of the potential change width Vc to the potential change width Vh has been adjusted based on information related to the viscosity of the ink acquired by the liquid information acquisition unit 200, and drives the active unit 310 with the ejection pulses DP10 to DP13 according to the ink viscosity, thereby making it possible to suppress variations in the ejection amount ejected from the nozzle 21 even when the viscosity of the ink changes. Incidentally, the flight speed of the ink ejected from the nozzle 21 also tends to change with changes in the viscosity of the ink in the same way as the ejection amount. For this reason, the adjustment unit 201 selects ejection pulses DP10 to DP13 according to the viscosity of the ink and drives the active unit 310 with the selected ejection pulses DP10 to DP13, making it possible to suppress variations in ejection characteristics such as the ejection amount and flight speed even when the viscosity of the ink changes.

[0156] In this embodiment, the potential change widths Vh10 to Vh13 of the contraction elements e3 to h3 of the ejection pulses DP10 to DP13 are equal, and the ratio of the potential change widths Vc10 to Vc13 of the expansion elements e1 to h1 to the potential change width Vh is changed to suppress variations in the amount of ink ejected. By making the potential change widths Vh10 to Vh13 equal, it is possible to reduce the amount of ink drawn in after ejection, making it difficult for air bubbles to be trapped in the nozzles 21 after ink ejection, suppressing ejection defects caused by trapped air bubbles and improving ejection stability. Furthermore, by making the potential change widths Vh10 to Vh13 equal, it is not necessary to make complex changes to the waveform shapes of the ejection pulses DP10 to DP13, making it easy to control the waveform shapes.

[0157] Of course, each of the potential change widths Vh10 to Vh13 may be changed depending on the viscosity of the ink. For example, when the viscosity of the ink is high, the potential change width Vh may be made relatively large, and when the viscosity of the ink is low, the potential change width Vh may be made relatively small. In other words, the potential change width Vh13 of the contraction element h3 of the ejection pulse DP13 may be adjusted to be larger than the potential change width Vh10 of the contraction element e3 of the ejection pulse DP10.

[0158] Furthermore, the ejection pulses DP10 to DP13 of this embodiment have the same potential change widths Vs1 to Vs4 of the re-expansion elements e5 to h5 that damp the vibration of the meniscus of the nozzle 21, so that the vibration inside the nozzle 21 after ejecting ink can be damped in the same way. Therefore, when ink is continuously ejected using each of the ejection pulses DP10 to DP13, it is possible to suppress changes in the state of residual vibration of the meniscus inside the nozzle 21 and suppress variations in the ejection amount. Therefore, with any of the ejection pulses DP10 to DP13, it is possible to suppress variations in the ejection amount when ink is continuously ejected, improving ejection stability.

[0159] In this embodiment, an ink viscosity of 9.2 m·Pas is an example of a "first viscosity," liquid information including this first viscosity is an example of "first information," and the ejection pulse DP12 is an example of a "first ejection pulse." Ink viscosities of 4 m·Pas, 8 m·Pas, and 12 m·Pas are examples of a "second viscosity," liquid information including this second viscosity is an example of "second information," and the ejection pulses DP10, DP11, and DP13 are examples of "second ejection pulses." When the above-mentioned "second viscosity" is lower than the "first viscosity," that is, when the "second viscosity" is 4 m·Pas or 8 m·Pas, the "second ejection pulse" becomes the ejection pulses DP10 and DP11. When the "second viscosity" is higher than the "first viscosity," that is, when the "second viscosity" is 12 m·Pas, the "second ejection pulse" becomes the ejection pulse DP13.

[0160] (Other embodiments) Although the embodiments of the present invention have been described above, the basic configuration of the present invention is not limited to those described above.

[0161] The adjustment unit 201 may adjust the potential change rate per unit time, or so-called slope, of the contraction elements a3 to h3 of each of the ejection pulses DP1 to DP4 and DP10 to DP13, in addition to adjusting the intermediate potentials Vm1 to Vm4 and Vm10 to Vm13 based on the liquid information acquired by the liquid information acquisition unit 200. For example, by reducing the potential change rate, or so-called slope, for low-viscosity ink and increasing the potential change rate, or so-called slope, for high-viscosity ink, it is possible to further reduce variations in the ejection volume and flight speed of the ejected ink even when the viscosity changes.

[0162] Although the liquid information acquisition unit 200 detects the viscosity of the ink from the residual vibration information, other methods may be used to estimate the viscosity of the ink. Ink viscosity is correlated with temperature; therefore, the lower the temperature, the higher the viscosity, and the higher the temperature, the lower the viscosity. Therefore, the liquid information acquisition unit 200 may detect the temperature of the ink, acquire temperature information related to the ink temperature, and estimate the viscosity of the ink. Furthermore, as the viscosity of the ink changes, the flight speed of the ink ejected from the nozzle 21 also changes. In other words, as the viscosity of the ink increases, the flight speed decreases. Therefore, the viscosity of the ink can be estimated by capturing and detecting the flight speed of the ink ejected from the nozzle 21 with a camera or the like. Alternatively, the ink ejected from the nozzle 21 may be landed on the medium S, and the flight speed may be estimated from the impact position, thereby estimating the viscosity of the ink. In any case, it is sufficient for the liquid information acquisition unit 200 to acquire the viscosity of the ink. Furthermore, if the user knows the viscosity of the ink, the liquid information acquisition unit 200 may acquire liquid information input by the user. Furthermore, the liquid information acquisition unit 200 may directly measure the amount of ink ejected from the nozzles 21. Such ink ejection amount can be measured, for example, by capturing an image of the flying ink and processing the image, or by image processing the size of the dots that have landed on the medium S. In other words, the "liquid information" may be residual vibration information that is essentially converted into ink viscosity, information related to the flight speed, or ink temperature information, or it may directly be the amount of ink ejected. Of course, the liquid information acquisition unit 200 may improve the accuracy of the liquid information by combining any two or more of the above to acquire multiple pieces of liquid information.

[0163] Furthermore, the adjustment unit 201 adjusts the intermediate potentials Vm1 to Vm4 and Vm10 to Vm13 so that variations in ejection characteristics, such as the ejection volume and flight speed of the ejected ink droplets, do not occur even when the liquid information changes, but this is not particularly limited. For example, the intermediate potentials Vm1 to Vm4 and Vm10 to Vm13 may be adjusted so that desired ejection characteristics are obtained according to the liquid information. In other words, the adjustment unit 201 may adjust the intermediate potential Vm so that desired small dots, medium dots, large dots, etc. are ejected according to the liquid information.

[0164] In addition, in the above-described embodiments, the thin-film piezoelectric actuator 300, essentially the active portion 310, has been described as the driving element that generates a pressure change in the pressure chamber 12. However, the present invention is not limited to this, and the driving element can be, for example, a thick-film piezoelectric actuator formed by attaching a green sheet or a longitudinal vibration type piezoelectric actuator in which piezoelectric material and electrode forming material are alternately laminated and expanded and contracted in the axial direction. In addition, the driving element can be, for example, an actuator in which a heating element is disposed in the pressure chamber 12 and bubbles generated by the heat generated by the heating element are used to eject droplets from the nozzle 21, or a so-called electrostatic actuator in which static electricity is generated between a vibration plate and an electrode, and the electrostatic force deforms the vibration plate to eject droplets from the nozzle 21.

[0165] Furthermore, in the above-described liquid ejection device 1, an example has been given in which the ejection section 2 is mounted on a holder 6a and moves in the main scanning direction, which is the Y-axis direction, but this is not particularly limited to this, and the present invention can also be applied to, for example, a so-called line printer in which the ejection section 2 is fixed and printing is performed simply by moving the medium S in the sub-scanning direction, which is the X-axis direction.

[0166] Furthermore, the present invention is broadly applicable to liquid ejection devices in general that are equipped with an ejection unit. Examples of the ejection unit include recording heads such as various inkjet recording heads used in image recording devices such as printers, and colorant ejection heads used in manufacturing color filters for liquid crystal displays and the like. Examples of the ejection unit include electrode material ejection heads used in forming electrodes for organic EL displays, FEDs (field emission displays), and the like, and bioorganic material ejection heads used in biochip manufacturing, and the present invention can also be applied to liquid ejection devices equipped with these ejection units.

[0167] (Addendum) From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0168] A method for driving a liquid ejection device according to a first preferred aspect is a method for driving a liquid ejection device having an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that imparts pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that imparts pressure fluctuations to the liquid in the pressure chamber so as to eject droplets from the nozzle, and the ejection pulse includes an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element. The terminal potential of the expansion element and the starting potential of the contraction element are equal, and the waveform shape of the ejection pulse is set according to the acquired liquid information, and if the acquired liquid information is first information corresponding to a first viscosity, a first ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set equal is supplied to the drive element, and if the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to different potentials is supplied to the drive element. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount and flight speed of droplets ejected from the nozzle even when the viscosity of the liquid changes.

[0169] In Aspect 2, which is a specific example of Aspect 1, when the second viscosity is lower than the first viscosity, the potential change width of the expansion element in the second ejection pulse is smaller than the potential change width of the contraction element. Thus, when the viscosity of the liquid is relatively low, the second ejection pulse can provide ejection characteristics equivalent to those of the first ejection pulse.

[0170] In Aspect 3, which is a specific example of Aspect 2, the second ejection pulse includes a re-expansion component that expands the pressure chamber after the contraction component. This allows the re-expansion component to damp vibration of the meniscus of the liquid in the nozzle.

[0171] In Aspect 4, which is a specific example of Aspect 3, the period from the start of the contraction element to the start of the re-expansion element of the second ejection pulse is 0.75 to 1.25 times the natural vibration period of the ejection unit, thereby enabling the re-expansion element to effectively damp vibration of the meniscus of the nozzle.

[0172] In Aspect 5, which is a specific example of Aspect 1, when the second viscosity is higher than the first viscosity, the potential change width of the expansion element is larger than the potential change width of the contraction element in the second ejection pulse. Thus, when the viscosity of the liquid is relatively high, the second ejection pulse can provide ejection characteristics equivalent to those of the first ejection pulse.

[0173] In Aspect 6, which is a specific example of Aspect 5, the second ejection pulse further includes a re-contraction element that further contracts the pressure chamber after the contraction element. This allows the re-contraction element to damp vibration of the meniscus of the liquid in the nozzle.

[0174] In Aspect 7, which is a specific example of Aspect 6, the period from the start of the contraction element to the start of the re-contraction element of the second ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejection unit, thereby enabling the re-contraction element to effectively damp vibration of the meniscus of the nozzle.

[0175] In Aspect 8, which is a specific example of Aspect 1, the period from the start of the expansion element to the start of the contraction element of the first ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejector, and the period from the start of the expansion element to the start of the contraction element of the second ejection pulse is 0.25 to 0.75 times the natural vibration period. This allows the contraction elements of the first and second ejection pulses to increase the ejection volume of droplets ejected from the nozzle.

[0176] In Aspect 9, which is a specific example of Aspect 1, the potential change width of the contraction element of the first ejection pulse is equal to the potential change width of the contraction element of the second ejection pulse. This makes it possible to suppress variations in ejection characteristics by making the potential change width of the contraction element equal and changing the potential change width of the expansion element, thereby suppressing bubbles from being entrained in the liquid in the nozzle by increasing the contraction element.

[0177] In Aspect 10, which is a specific example of Aspect 1, the liquid information includes residual vibration information corresponding to residual vibration of the liquid in the pressure chamber. By acquiring the residual vibration information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and variations in the ejection characteristics of the ejected droplets can be suppressed even if the viscosity of the liquid changes.

[0178] In Aspect 11, which is a specific example of Aspect 1, the liquid information includes temperature information corresponding to the temperature of the liquid. By acquiring the temperature information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and variations in the ejection characteristics of the ejected droplets can be suppressed even if the viscosity of the liquid changes.

[0179] In Aspect 12, which is a specific example of Aspect 1, the liquid information includes the liquid information input by a user.

[0180] A preferred embodiment of a method for driving a liquid ejection device according to Aspect 13 is a method for driving a liquid ejection device having an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse includes an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element. the terminal potential of the expansion element and the starting potential of the contraction element are equal, the waveform shape of the ejection pulse is set according to the acquired liquid information, when the acquired liquid information is third information corresponding to a third viscosity, a third ejection pulse in which the potential change width of the expansion element is set smaller than the potential change width of the contraction element is supplied to the drive element, and when the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity, a fourth ejection pulse in which the potential change width of the expansion element is set larger than the potential change width of the contraction element is supplied to the drive element. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount and flight speed of droplets ejected from the nozzle even when the viscosity of the liquid changes.

[0181] In Aspect 14, which is a specific example of Aspect 13, the third ejection pulse includes a re-expansion component that expands the pressure chamber after the contraction component. This allows the re-expansion component to damp vibration of the meniscus of the liquid in the nozzle.

[0182] In Aspect 15, which is a specific example of Aspect 14, the period from the start of the contraction element to the start of the re-expansion element of the third ejection pulse is 0.75 to 1.25 times the natural vibration period of the ejection unit, thereby enabling the re-expansion element to effectively damp vibration of the meniscus of the nozzle.

[0183] In Aspect 16, which is a specific example of Aspect 13, the fourth ejection pulse includes a re-contraction element that further contracts the pressure chamber after the contraction element. This allows the re-contraction element to damp vibration of the meniscus of the liquid in the nozzle.

[0184] In Aspect 17, which is a specific example of Aspect 16, the period from the start of the contraction element to the start of the re-contraction element of the fourth ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejection unit, thereby enabling the re-contraction element to effectively damp vibration of the meniscus of the nozzle.

[0185] In Aspect 18, which is a specific example of Aspect 13, the period from the start of the expansion element to the start of the contraction element of the third ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejector, and the period from the start of the expansion element to the start of the contraction element of the fourth ejection pulse is 0.25 to 0.75 times the natural vibration period. This allows the ejection volume of droplets ejected from the nozzle by the contraction elements of the first and second ejection pulses to be increased.

[0186] In Aspect 19, which is a specific example of Aspect 13, the potential change width of the contraction element of the third ejection pulse is equal to the potential change width of the contraction element of the fourth ejection pulse. This makes it possible to suppress variations in ejection characteristics by making the potential change width of the contraction element equal and changing the potential change width of the expansion element, and therefore makes it possible to suppress bubbles from being entrained in the liquid in the nozzle by increasing the contraction element.

[0187] In Aspect 20, which is a specific example of Aspect 13, the liquid information includes residual vibration information corresponding to residual vibration of the liquid in the pressure chamber. By acquiring the residual vibration information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and variations in the ejection characteristics of the ejected droplets can be suppressed even if the viscosity of the liquid changes.

[0188] In Aspect 21, which is a specific example of Aspect 13, the liquid information includes temperature information corresponding to the temperature of the liquid. By acquiring the temperature information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and variations in the ejection characteristics of the ejected droplets can be suppressed even if the viscosity of the liquid changes.

[0189] In a twenty-second embodiment that is a specific example of the thirteenth embodiment, the liquid information includes the liquid information input by a user.

[0190] A preferred aspect of a driving method for a liquid ejection device according to aspect 23 is a driving method for a liquid ejection device having an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse includes an expansion element that changes in potential to expand the pressure chamber, a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element, and a re-expansion element that changes in potential to expand the pressure chamber contracted by the contraction element, and The starting potential of the contraction element is equal, the terminal potential of the contraction element is equal to the starting potential of the re-expansion element, and the waveform shape of the ejection pulse is set according to the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, the potential change width of the expansion element is set equal to the potential change width of the contraction element, and a first ejection pulse having a re-contraction element whose potential changes so as to contract the pressure chamber expanded by the re-expansion element is supplied to the drive element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set to different potentials is supplied to the drive element. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount and flight speed of droplets ejected from the nozzle even when the viscosity of the liquid changes.

[0191] In Aspect 24, which is a specific example of Aspect 23, when the second viscosity is lower than the first viscosity, the potential change width of the expansion element in the second ejection pulse is smaller than the potential change width of the contraction element. Thus, when the viscosity of the liquid is relatively low, the second ejection pulse can provide ejection characteristics equivalent to those of the first ejection pulse.

[0192] In Aspect 25, which is a specific example of Aspect 24, the second ejection pulse has a re-contraction element that changes potential so as to contract the pressure chamber expanded by the re-expansion element. This allows the re-contraction element to damp vibration of the meniscus of the liquid in the nozzle.

[0193] In Aspect 26, which is a specific example of Aspect 25, the period from the start of the contraction element to the start of the re-contraction element in the second ejection pulse is 1.25 to 1.75 times the natural vibration period of the ejection unit, thereby enabling the re-contraction element to effectively damp vibration of the meniscus of the nozzle.

[0194] In Aspect 27, which is a specific example of Aspect 23, when the second viscosity is higher than the first viscosity, the potential change width of the expansion element is higher than the potential change width of the contraction element in the second ejection pulse. Thus, when the viscosity of the liquid is relatively high, the second ejection pulse can achieve ejection characteristics equivalent to those of the first ejection pulse.

[0195] In Aspect 28, which is a specific example of Aspect 27, the second ejection pulse includes a re-contraction element that contracts the pressure chamber after the re-expansion element, and in the second ejection pulse, the starting potential of the expansion element is equal to the ending potential of the re-contraction element. This allows the re-contraction element to damp vibration of the meniscus of the liquid in the nozzle.

[0196] In Aspect 29, which is a specific example of Aspect 28, the period from the start of the contraction element to the start of the re-contraction element in the second ejection pulse is 1.25 to 1.75 times the natural vibration period of the ejection unit. This allows the re-contraction element to effectively damp vibration of the meniscus of the nozzle.

[0197] In Aspect 30, which is a specific example of Aspect 23, in the first ejection pulse, the period from the start of the contraction element to the start of the re-expansion element is 0.75 to 1.25 times the natural vibration period of the ejection section, and in the second ejection pulse, the period from the start of the contraction element to the start of the re-expansion element is 0.75 to 1.25 times the natural vibration period. This allows the re-expansion element to effectively damp vibration of the meniscus of the nozzle.

[0198] In Aspect 31, which is a specific example of Aspect 23, the period from the start of the contraction element to the start of the re-contraction element in the first ejection pulse is 1.25 to 1.75 times the natural vibration period of the ejection unit, thereby enabling the re-contraction element to effectively damp vibration of the meniscus of the nozzle.

[0199] In Aspect 32, which is a specific example of Aspect 23, the period from the start of the expansion element to the start of the contraction element of the first ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejector, and the period from the start of the expansion element to the start of the contraction element of the second ejection pulse is 0.25 to 0.75 times the natural vibration period. This allows the contraction elements of the first and second ejection pulses to increase the ejection volume of droplets ejected from the nozzle.

[0200] In Aspect 33, which is a specific example of Aspect 23, the potential change width of the contraction element of the first ejection pulse is equal to the potential change width of the contraction element of the second ejection pulse. This makes it possible to suppress variations in ejection characteristics by making the potential change width of the contraction element equal and changing the potential change width of the expansion element, and therefore makes it possible to suppress bubbles from being entrained in the liquid in the nozzle by increasing the contraction element.

[0201] In Aspect 34, which is a specific example of Aspect 23, the potential change width of the re-expansion element of the first ejection pulse is equal to the potential change width of the re-expansion element of the second ejection pulse. This allows the first ejection pulse and the second ejection pulse to similarly suppress vibration of the nozzle meniscus after ejecting droplets, thereby preventing variations in ejection characteristics when droplets are continuously ejected.

[0202] In Aspect 35, which is a specific example of Aspect 23, the period from the start of the expansion element to the start of the contraction element of the first ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejector, and the period from the start of the expansion element to the start of the contraction element of the second ejection pulse is 0.25 to 0.75 times the natural vibration period. This allows the contraction elements of the first and second ejection pulses to increase the ejection volume of droplets ejected from the nozzle.

[0203] In Aspect 36, which is a specific example of Aspect 23, the liquid information includes residual vibration information corresponding to residual vibration of the liquid in the pressure chamber. By acquiring the residual vibration information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and variations in the ejection characteristics of the ejected droplets can be suppressed even if the viscosity of the liquid changes.

[0204] In Aspect 37, which is a specific example of Aspect 23, the liquid information includes temperature information corresponding to the temperature of the liquid. According to this, by acquiring the temperature information of the liquid, the viscosity of the liquid can be estimated easily and with high accuracy, and even if the viscosity of the liquid changes, variations in the ejection characteristics of the ejected droplets can be suppressed.

[0205] In Example 38, which is a specific example of Example 23, the liquid information includes the liquid information input by a user.

[0206] A method for driving a liquid ejection device according to a thirty-ninth aspect, which is a preferred aspect, includes an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse has an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element. and an element, wherein the terminal potential of the expansion element and the starting potential of the contraction element are equal, and the control unit sets the waveform shape of the ejection pulse according to the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, the control unit supplies to the drive element a first ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set equal, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, the control unit supplies to the drive element a second ejection pulse in which the potential change width of the expansion element and the potential change width of the contraction element are set differently. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount, which is the weight of the droplets ejected from the nozzle, and the flight speed, even when the viscosity of the liquid changes.

[0207] A method for driving a liquid ejection device according to a fortyth preferred aspect includes an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse has an expansion element that changes in potential to expand the pressure chamber, and a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element. and an element, wherein an end potential of the expansion element and a starting potential of the contraction element are equal, and the control unit sets a waveform shape of the ejection pulse according to the acquired liquid information, and when the acquired liquid information is third information corresponding to a third viscosity, the control unit supplies to the drive element a third ejection pulse in which a potential change width of the expansion element is set smaller than a potential change width of the contraction element, and when the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity, the control unit supplies to the drive element a fourth ejection pulse in which a potential change width of the expansion element is set larger than a potential change width of the contraction element. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount, which is the weight of the droplets ejected from the nozzle, and the flight speed, even when the viscosity of the liquid changes.

[0208] A method for driving a liquid ejection device according to aspect 41, which is a preferred aspect, includes an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber, and a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element, wherein the drive signal has an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the ejection pulse includes an expansion element that changes in potential to expand the pressure chamber, a contraction element that changes in potential to contract the pressure chamber expanded by the expansion element, and a re-expansion element that changes in potential to expand the pressure chamber contracted by the contraction element, and The control unit sets the waveform of the ejection pulse in accordance with the acquired liquid information, and when the acquired liquid information is first information corresponding to a first viscosity, the control unit supplies to the drive element a first ejection pulse having a re-contraction element whose potential change width is set equal to the expansion element and whose potential change width is set equal to contraction element, and whose potential change width is set to contract the pressure chamber expanded by the re-expansion element, and when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, the control unit supplies to the drive element a second ejection pulse having a potential change width of the expansion element and whose potential change width is set different from the contraction element. According to this, by changing the ratio of the potential change width of the expansion element to the potential change width of the contraction element, it is possible to suppress variations in ejection characteristics such as the ejection amount, which is the weight of the droplets ejected from the nozzle, and the flight speed, even when the viscosity of the liquid changes. [Explanation of symbols]

[0209] COM... drive signal, DP1 to DP4, DP10 to DP13... ejection pulse, S... medium, T... drive cycle, Tc... natural vibration cycle, 1... liquid ejection device, 2... ejection section, 3... liquid storage section, 4... control section, 5... transport mechanism, 6... movement mechanism, 10... pressure chamber substrate, 12... pressure chamber, 15... communication plate, 20... nozzle plate, 21... nozzle, 30... protection substrate, 32... through hole, 40... case member, 45... compliance substrate, 50... vibration plate, 60... first electrode, 70... piezoelectric body Layer, 80...second electrode, 91...lead electrode, 100...common liquid chamber, 110...wiring member, 111...drive circuit, 112...detection circuit, 200...liquid information acquisition unit, 201...adjustment unit, 211...external interface, 212A...receiving buffer, 212B...intermediate buffer, 212C...output buffer, 214...control processing unit, 215...oscillating circuit, 216...drive signal generation circuit, 217...internal interface, 300...piezoelectric actuator, 310...active unit.

Claims

1. A method for driving a liquid ejecting device having a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, the method comprising: the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, and a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, The waveform shape of the ejection pulse is set according to the acquired liquid information, When the acquired liquid information is first information corresponding to a first viscosity, a first ejection pulse is supplied to the drive element, in which a potential change width of the expansion element and a potential change width of the contraction element are set equal to each other; When the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse is supplied to the drive element, in which a potential change width of the expansion element and a potential change width of the contraction element are set to different potentials. A method for driving a liquid ejection device.

2. If the second viscosity is lower than the first viscosity, In the second ejection pulse, a potential change width of the expansion element is smaller than a potential change width of the contraction element.

2. The method for driving a liquid ejection apparatus according to claim 1.

3. If the second viscosity is higher than the first viscosity, In the second ejection pulse, a potential change width of the expansion element is larger than a potential change width of the contraction element.

2. The method for driving a liquid ejection apparatus according to claim 1.

4. a potential change width of the contraction element of the first ejection pulse is equal to a potential change width of the contraction element of the second ejection pulse; 2. The method for driving a liquid ejection apparatus according to claim 1.

5. The liquid information is residual vibration information corresponding to residual vibration of the liquid in the pressure chamber; temperature information corresponding to the temperature of the liquid; The liquid information input by the user; at least one of 2. The method for driving a liquid ejection apparatus according to claim 1.

6. A method for driving a liquid ejecting device having a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, the method comprising: the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, and a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, The waveform shape of the ejection pulse is set according to the acquired liquid information, When the acquired liquid information is third information corresponding to a third viscosity, a third ejection pulse is supplied to the drive element, in which a potential change width of the expansion element is set smaller than a potential change width of the contraction element, When the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity, a fourth ejection pulse is supplied to the drive element, in which a potential change width of the expansion element is set larger than a potential change width of the contraction element. A method for driving a liquid ejection device.

7. a period from the start of the expansion element to the start of the contraction element of the third ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejection portion, a period from the start of the expansion element to the start of the contraction element of the fourth ejection pulse is 0.25 to 0.75 times the natural vibration period; 7. The method for driving a liquid ejection apparatus according to claim 6.

8. a potential change width of the contraction element of the third ejection pulse is equal to a potential change width of the contraction element of the fourth ejection pulse; 7. The method for driving a liquid ejection apparatus according to claim 6.

9. The liquid information is residual vibration information corresponding to residual vibration of the liquid in the pressure chamber; temperature information corresponding to the temperature of the liquid; The liquid information input by the user; at least one of 7. The method for driving a liquid ejection apparatus according to claim 6.

10. A method for driving a liquid ejecting device having a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber in response to a supplied drive signal, the method comprising: the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, and a re-expansion element whose potential changes so as to expand the pressure chamber contracted by the contraction element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, The end potential of the contraction element and the beginning potential of the re-expansion element are equal, The waveform shape of the ejection pulse is set according to the acquired liquid information, When the acquired liquid information is first information corresponding to a first viscosity, a potential change width of the expansion element and a potential change width of the contraction element are set equal, and a first ejection pulse having a re-contraction element whose potential changes so as to contract the pressure chamber expanded by the re-expansion element is supplied to the drive element; When the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity, a second ejection pulse is supplied to the drive element, in which a potential change width of the expansion element and a potential change width of the contraction element are set to different potentials. A method for driving a liquid ejection device.

11. When the second viscosity is lower than the first viscosity, In the second ejection pulse, a potential change width of the expansion element is smaller than a potential change width of the contraction element. The method for driving a liquid ejection apparatus according to claim 10 .

12. When the second viscosity is higher than the first viscosity, In the second ejection pulse, a potential change width of the expansion element is higher than a potential change width of the contraction element. The method for driving a liquid ejection apparatus according to claim 10 .

13. a period from the start of the expansion element to the start of the contraction element of the first ejection pulse is 0.25 to 0.75 times the natural vibration period of the ejection portion, a period from the start of the expansion element to the start of the contraction element of the second ejection pulse is 0.25 to 0.75 times the natural vibration period; The method for driving a liquid ejection apparatus according to claim 10 .

14. a potential change width of the contraction element of the first ejection pulse and a potential change width of the contraction element of the second ejection pulse are equal; The method for driving a liquid ejection apparatus according to claim 10 .

15. a potential change width of the re-expansion element of the first ejection pulse and a potential change width of the re-expansion element of the second ejection pulse are equal; The method for driving a liquid ejection apparatus according to claim 10 .

16. The liquid information is residual vibration information corresponding to residual vibration of the liquid in the pressure chamber; temperature information corresponding to the temperature of the liquid; The liquid information input by the user; at least one of The method for driving a liquid ejection apparatus according to claim 10 .

17. a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber; a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element; Equipped with the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, and a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, the control unit sets a waveform shape of the ejection pulse in accordance with the acquired liquid information, If the acquired liquid information is first information corresponding to a first viscosity, a first ejection pulse is supplied to the drive element, in which a potential change width of the expansion element and a potential change width of the contraction element are set equal; supplying, to the driving element, a second ejection pulse in which a potential change width of the expansion element and a potential change width of the contraction element are set to different potentials when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity; A liquid ejection device characterized by:

18. a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber; a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element; Equipped with the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, and a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, the control unit sets a waveform shape of the ejection pulse in accordance with the acquired liquid information, If the acquired liquid information is third information corresponding to a third viscosity, a third ejection pulse is supplied to the drive element, in which a potential change width of the expansion element is set smaller than a potential change width of the contraction element; supplying, to the driving element, a fourth ejection pulse in which a potential change width of the expansion element is set larger than a potential change width of the contraction element, when the acquired liquid information is fourth information corresponding to a fourth viscosity different from the third viscosity; A liquid ejection device characterized by:

19. a discharge unit including a nozzle that ejects liquid as droplets, a pressure chamber that communicates with the nozzle, and a drive element that applies pressure fluctuations to the liquid in the pressure chamber; a control unit that acquires liquid information including information about the liquid and supplies a drive signal to the drive element; Equipped with the drive signal has an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so as to eject droplets from the nozzle; the ejection pulse includes an expansion element whose potential changes so as to expand the pressure chamber, a contraction element whose potential changes so as to contract the pressure chamber expanded by the expansion element, and a re-expansion element whose potential changes so as to expand the pressure chamber contracted by the contraction element, The terminal potential of the expansion element is equal to the starting potential of the contraction element, The end potential of the contraction element is equal to the beginning potential of the expansion element, the control unit sets a waveform shape of the ejection pulse in accordance with the acquired liquid information, When the acquired liquid information is first information corresponding to a first viscosity, a potential change width of the expansion element and a potential change width of the contraction element are set equal, and a first ejection pulse having a re-contraction element whose potential changes so as to contract the pressure chamber expanded by the re-expansion element is supplied to the drive element; supplying, to the driving element, a second ejection pulse in which a potential change width of the expansion element and a potential change width of the contraction element are set to different potentials when the acquired liquid information is second information corresponding to a second viscosity different from the first viscosity; A liquid ejection device characterized by:

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