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 method of driving a liquid ejecting apparatus including an ejection section 2 including a nozzle that ejects a liquid as a liquid droplet, a pressure chamber that communicates with the nozzle, and a drive element 310 that applies a pressure fluctuation to the liquid in the pressure chamber according to a supplied drive signal, the method comprising: The drive signal includes a pre-vibration pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that a liquid droplet is not ejected from the nozzle, and a discharge pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that a liquid droplet is ejected from the nozzle, and an interval between the pre-vibration pulse and the discharge pulse is set according to the acquired liquid information.SELECTED DRAWING: Figure 5

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 section includes a nozzle that ejects liquid, a pressure chamber that communicates with the nozzle, and a drive element that generates pressure fluctuations in the liquid in the pressure chamber.

[0004] A driving method has been proposed in which a pre-vibration pulse that does not eject liquid is supplied to the driving element of such a liquid ejection head before an ejection pulse is supplied, thereby ejecting a weight of liquid that is heavier than the weight of liquid that would be ejected if only the ejection pulse were used (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-280475 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the state of the liquid, for example, the temperature, viscosity, composition, etc. of the liquid, changes, the pressure fluctuations due to the pre-vibration pulse and ejection pulse change, and the desired ejection characteristics such as flight speed and weight may not be obtained, or ejection failure may occur in which the liquid is not ejected. [Means for solving the problem]

[0007] An aspect of the present invention that solves the above problem is a method for driving a liquid ejection device having an ejection section that includes 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 includes a pre-vibration pulse that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are not ejected from the nozzle, and an ejection pulse that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the method for driving a liquid ejection device is characterized in that the interval between the pre-vibration pulse and the ejection pulse is set in response to acquired liquid information.

[0008] Another aspect of the present invention is a liquid injection device comprising: an ejection unit having a nozzle that ejects liquid as droplets, a pressure chamber connected to the nozzle, and a drive element that imparts 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 pre-vibration pulse that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are not ejected from the nozzle, and an ejection pulse that imparts pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle, and the control unit sets the interval between the pre-vibration pulse and the ejection pulse according to the acquired liquid information. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a liquid ejecting apparatus. [Figure 2] FIG. [Figure 3] FIG. 2 is a block diagram showing an electrical configuration of the liquid ejection device. [Figure 4] 1 shows a drive waveform of a drive signal. [Figure 5] FIG. 2 is a block diagram showing a function realization unit of a control unit. [Figure 6] 10 is a graph showing the relationship between the interval t1 and the ink weight. [Figure 7]10 shows the drive waveform of a drive signal with an adjusted interval. [Figure 8] 10 shows the drive waveform of a drive signal with an adjusted interval. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] (Embodiment 1) FIG. 1 is a diagram showing a schematic configuration of a liquid ejecting apparatus 1 of the present invention.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The material of the nozzle plate 20 is not particularly limited, and for example, a silicon substrate or the like can be used.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 larger 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Here, the control unit 4 generates the drive signal COM based on reference drive waveform information, which is information on the optimal drive waveform for stably ejecting liquid in accordance with reference liquid information, which is information on the liquid that serves as a reference in the initial state.

[0044] An example of the standard drive signal COM will now be described with reference to Fig. 4. Fig. 4 is a waveform diagram showing the drive signal COM of this embodiment.

[0045] 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 a recording period T, and corresponds to one pixel of an image to be printed on the medium S.

[0046] 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.

[0047] The drive signal COM is a signal that has one pre-vibration pulse PVP and one ejection pulse DP in this order within one drive period T, and is repeatedly generated for each drive period T by the drive signal generation circuit 216.

[0048] The pre-vibration pulse PVP has a first expansion element a1, a first expansion maintaining element a2, and a first contraction element a3, which are successively arranged in this order in time series.

[0049] The first expansion element a1 changes the potential from the reference potential V0 to the first potential V1, thereby expanding the volume of the pressure chamber 12 from the reference volume. This first expansion element a1 draws the ink liquid surface in the nozzle 21, the so-called meniscus, toward the pressure chamber 12. The first expansion maintenance element a2 maintains the first potential V1 for a fixed period of time. While the first expansion maintenance element a2 is being supplied, pressure oscillations occur in the liquid in the pressure chamber 12 with a natural oscillation period Tc. The period of this pressure oscillation of the liquid in the pressure chamber 12, the so-called natural oscillation period Tc, can generally be expressed by the following equation (1):

[0050]

number

[0051] 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).

[0052]

number

[0053] 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).

[0054]

number

[0055] The first contraction element a3 changes the potential from the first potential V1 to the reference potential V0, contracting the volume of the pressure chamber 12 and returning it to the reference volume. The first contraction element a3 has a potential change rate and a potential change width per unit time that are large enough to prevent ink from being ejected from the nozzle 21.

[0056] The total time of the first expansion component a1 and the first expansion maintenance component a2 is preferably 0.45 to 0.55 times the natural vibration period Tc of the ejection section 2. By setting the time of the first expansion component a1 and the first expansion maintenance component a2 within the above range, the ink meniscus of the nozzle 21 can be stably and largely vibrated, and the weight of the ink can be increased when the ink is ejected by the subsequent ejection pulse DP.

[0057] The ejection pulse DP includes a second expansion element b1, a second expansion maintaining element b2, a second contraction element b3, a second contraction maintaining element b4, a third expansion element b5, a third expansion maintaining element b6, and a third contraction element b7.

[0058] The second expansion element b1 changes the potential from the reference potential V0 to a second potential V2, causing the volume of the pressure chamber 12 to expand from the reference volume. This second expansion element b1 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 second expansion maintenance element b2 maintains the second potential V2 for a fixed period of time. While the second expansion maintenance element b2 is being supplied, pressure vibrations occur in the liquid in the pressure chamber 12 due to the natural vibration period Tc.

[0059] The second contraction element b3 contracts the volume of the pressure chamber 12 from the second potential V2 to the reference potential V0, causing ink to be ejected from the nozzle 21. The potential change width of the second contraction element b3 from the second potential V2 to the reference potential V0 is referred to as the potential difference Vh2.

[0060] The period from the start of the second expansion component b1 to the end of the second expansion maintenance component b2, i.e., the start of the second contraction component b3, is appropriately set, for example, to 1 / 2 the natural vibration period Tc. The vibrations within the pressure chamber 12 caused by the expansion of the pressure chamber 12 by the second expansion component b1 remain as residual vibrations (residual vibrations of the meniscus of the nozzle 21) due to the natural vibration period Tc even after the second expansion maintenance component b2, significantly affecting the contraction of the pressure chamber 12 by the second contraction component b3. For example, if the second contraction component b3 is initiated while the meniscus is vibrating in a direction protruding away from the pressure chamber 12, the ink weight tends to increase. Conversely, if the second contraction component b3 is initiated while the meniscus is vibrating in a direction retracting toward the pressure chamber 12, the ink weight tends to decrease.

[0061] The second contraction sustaining element b4 sustains the reference potential V0, which is the potential at the end point of the second contraction element b3, for a certain period of time. While the second contraction sustaining element b4 is supplied to the active portion 310, pressure vibration occurs in the ink in the pressure chamber 12 with the natural vibration period Tc.

[0062] The third expansion element b5 changes the potential from the reference potential V0 to a third potential V3, expanding the volume of the pressure chamber 12. This third expansion element b5 weakens the pressure vibration of the ink in the pressure chamber 12, i.e., the residual vibration of the meniscus. The period from the start of the second contraction element b3 to the start of the third expansion element b5 is appropriately set, for example, with the vicinity of the natural vibration period Tc as a guide. In other words, as described above, by starting the third expansion element b5 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.

[0063] The third expansion maintaining element b6 maintains the third potential V3 for a certain period of time. The third contraction element b7 changes the potential from the third potential V3 to the reference potential V0, contracting the volume of the pressure chamber 12 to the reference volume. The third contraction element b7 weakens the pressure vibration of the ink in the pressure chamber 12, i.e., the residual vibration of the meniscus. Similarly, by starting the third contraction element b7 while the meniscus is vibrating in a direction pulling it into the nozzle 21, the residual vibration of the meniscus is weakened and the vibration of the meniscus can be damped relatively quickly. In other words, the third expansion element b5 to the third contraction element b7 function as vibration damping elements that damp the vibration of the ink in the pressure chamber 12, i.e., the residual vibration of the meniscus.

[0064] Between such a pre-vibration pulse PVP and the ejection pulse DP, there is an intermediate element c1 that maintains the reference potential V0 for a certain period of time.

[0065] By ejecting ink using the pre-oscillation pulse PVP and the ejection pulse DP in this way, the weight of the ejected ink can be increased compared to when ink is ejected using only the ejection pulse DP. Incidentally, in order to increase the weight of ink ejected using only the ejection pulse DP, there is a limit to the potential change width, which limits the pressure fluctuation and makes it difficult to increase the ink weight. By pre-oscillating using the pre-oscillation pulse PVP in addition to the ejection pulse DP as in this embodiment, the ink weight can be easily increased without significantly changing the potential change width of the ejection pulse DP.

[0066] Of course, when a large ink weight is not required, the control unit 4 can also eject ink using only the ejection pulse DP without applying the pre-vibration pulse PVP to the active unit 310. In other words, the control unit 4 can appropriately select, depending on the image to be printed, whether to drive the active unit 310 using only the ejection pulse DP to eject ink, or to drive the active unit 310 using both the pre-vibration pulse PVP and the ejection pulse DP to eject ink.

[0067] The interval between the pre-oscillation pulse PVP and the ejection pulse DP, i.e., the interval t1 between the start point of the first contraction element a3 of the pre-oscillation pulse PVP and the start point of the second contraction element b3 of the ejection pulse DP, is set in advance in the initial state (at the time of shipping from the factory) based on reference drive waveform information corresponding to reference liquid information, which is information about the reference ink. That is, since the viscosity of ink varies depending on the ink, the drive signal COM is set based on the reference drive waveform information in which the interval t1 is set so that the ink ejection amount, flight speed, shape, etc. are optimized according to the viscosity of the reference ink. Note that the reference ink is, for example, a liquid managed and manufactured by the manufacturer of the liquid ejection device 1, and the manufacturer knows its characteristics. As a result, it is possible to set the elements a1 to a3, b1 to b7, and c1 of the pre-oscillation pulse PVP and the ejection pulse DP with an appropriate interval t1.

[0068] Furthermore, the potential change width of the pre-vibration pulse PVP, i.e., the potential difference Vh1 between the reference potential V0 and the first potential V1, is smaller than the potential change width of the ejection pulse DP, i.e., the potential difference Vh2 between the reference potential V0 and the second potential V2. Furthermore, the potential change rate per unit time of the first contraction element a3 of the pre-vibration pulse PVP, i.e., the so-called gradient, is smaller than the potential change rate per unit time of the second contraction element b3 of the ejection pulse DP, i.e., the so-called gradient. As a result, ink is not ejected by the pre-vibration pulse PVP, and ink with excellent ink weight and flying speed can be ejected by the ejection pulse DP.

[0069] 5 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, a distance adjustment unit 201, and a storage unit 202.

[0070] 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 liquid 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, amplitude, or vibration damping state of the residual vibration. The liquid information acquisition unit 200 can acquire the residual vibration information, for example, by 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 liquid in the pressure chamber 12 after the active portion 310 is driven, and analyzing the residual vibration signal. The liquid viscosity can be calculated from the information related to the residual vibration acquired in this manner, i.e., the period Tr, amplitude, and vibration damping state. In other words, if the viscosity of the liquid 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 viscosity of the liquid and the period, amplitude, and vibration attenuation state of the residual vibration, the viscosity of the liquid can be estimated 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.

[0071] The reference liquid information, which is the reference value of the liquid information, i.e., the initial value of the residual vibration information, may be a value acquired or calculated using a reference ink and used to set each element of the pre-vibration pulse PVP and the ejection pulse DP of the drive signal COM. Such reference values ​​of the liquid information are stored in the memory unit 202. In this embodiment, the memory unit 202 is, for example, a ROM 213 provided in the control unit 4. Of course, the memory unit 202 is not limited to the ROM 213, and may be a memory element other than the ROM 213 if the control unit 4 is provided with such a memory element. Furthermore, the memory unit 202 is not limited to a memory element provided in the control unit 4, and may 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, for example, a memory element built into the drive circuit 111 or the detection circuit 112. Furthermore, if the ejection unit 2 is equipped with a memory element other than the drive circuit 111 or the detection circuit 112, the memory unit 202 may be stored therein. Of course, the memory unit 202 may be a memory element provided outside the ejection unit 2.

[0072] The storage unit 202 also stores reference waveform information, which is a reference value of the drive waveform corresponding to reference liquid information, which is a reference value of the liquid information. By storing the reference liquid information and the corresponding reference waveform information in the storage unit 202 in this way, it is possible to set the elements of the drive signal COM, i.e., the pre-vibration pulse PVP and the ejection pulse DP, that have an optimal waveform shape in accordance with the reference value of the liquid information.

[0073] The interval adjustment unit 201 compares the liquid information acquired by the liquid information acquisition unit 200 with reference liquid information, which is a reference value of the liquid information stored in the memory unit 202, and if the liquid information acquired by the liquid information acquisition unit 200 differs from the reference value, the interval adjustment unit 201 causes the drive signal generation circuit 216 to generate a drive signal COM with the interval t1 adjusted relative to the reference waveform information stored in the memory unit 202.

[0074] The interval t1 adjusted by the interval adjustment unit 201 may be determined, for example, by preparing a two-dimensional table in advance that associates the difference between the liquid information acquired by the liquid information acquisition unit 200 and a reference value of the liquid information with the interval t1, and the interval adjustment unit 201 adjusting the interval t1 based on this two-dimensional table. The two-dimensional table may be created based on the relationship between the liquid information in the discharge unit 2 and the weight of the liquid ejected from the nozzle 21, and the two-dimensional table may be stored in the storage unit 202. Of course, the amount of adjustment of the interval t1 by the interval adjustment unit 201 may also be obtained by calculation based on an equation derived from the relationship between the liquid information and the weight of the ejected liquid.

[0075] Here, when the interval t1 between the pre-vibration pulse PVP and the ejection pulse DP is (n × Tc) (n is a natural number), the weight of ink ejected from the nozzle 21 is maximum, and when it is (n + 0.5) × Tc (n is a natural number), the weight of ink ejected from the nozzle 21 is minimum. This is because, as described above, the pre-vibration pulse PVP causes the ink meniscus of the nozzle 21 to vibrate at the natural vibration period Tc, and if the second contraction element b3 of the ejection pulse DP starts while the meniscus is vibrating in the direction opposite to the pressure chamber 12, the weight of the ink increases. Conversely, if the second contraction element b3 starts while the meniscus is vibrating in the direction drawn toward the pressure chamber 12, the weight of the ink decreases.

[0076] 6 is a graph showing the relationship between the difference [μsec] between the interval t1 and the natural vibration period Tc in the drive signal COM and the weight [ng] of ink ejected from the nozzle 21 for inks of different viscosities. In FIG. 6, low-viscosity ink is shown by a solid line, and high-viscosity ink is shown by a dashed line.

[0077] 6, the weight of ink ejected from the nozzle 21 changes as the difference between the interval t1 and the natural vibration period Tc varies. Specifically, the weight of ink ejected is the highest when the difference between the interval t1 and the natural vibration period Tc is 0 (zero). Furthermore, when high-viscosity ink is used, the weight of ink ejected is generally lower than when low-viscosity ink is used, even when driven with the same drive signal COM.

[0078] 6, for example, when the difference between the interval t1 and the natural vibration period Tc of high-viscosity ink is 0 (zero), the weight of the ink is 10.7 [ng], whereas when low-viscosity ink is ejected at the same interval t1, the ink weight becomes 12.5 [ng]. Therefore, when ejecting low-viscosity ink, the difference between the interval t1 and the natural vibration period Tc is changed to 1.75 [μsec] so that the weight of the ink becomes 10.7 [ng].

[0079] For this reason, the interval adjustment unit 201 calculates the viscosity of the ink from the liquid information including residual vibration information, which is information regarding residual vibration acquired by the liquid information acquisition unit 200, and adjusts the shape of the reference drive waveform so that the interval t1 is appropriate for the ink viscosity, so that there is no variation in the weight of the ink ejected.

[0080] For example, when the viscosity of the reference ink is high, the reference drive waveform shown in FIG. 4 is used. For example, the difference between the interval t1 shown in FIG. 4 and the natural vibration period Tc is set to 0 (zero), i.e., (n×Tc) (n is a natural number). On the other hand, when the ink viscosity is low, the interval adjustment unit 201 sets the interval t2 shorter than the interval t1 as shown in FIG. 7, or sets the interval t3 longer than the interval t1 as shown in FIG. 8, thereby setting the intervals t2 and t3 to (n±α)×Tc. By adjusting the interval t1 to the interval t2 or the interval t3 in this manner, it is possible to suppress variations in the weight of ink ejected between high-viscosity ink and low-viscosity ink. The same tendency also applies to the flight speed of ink ejected from the nozzle 21.

[0081] In the above example, the reference ink viscosity is an example of liquid information for a "first state," and the interval t1 set in accordance with the liquid information for this first state is an example of a "first interval." From this state, an ink viscosity lower than the reference ink viscosity is an example of liquid information for a "second state," and the intervals t1 and t2 set in accordance with the liquid information for this second state are examples of a "second interval." In other words, the interval t1, which is the first interval for the first state, is set to a value closer to n times the natural vibration period Tc (n is a natural number greater than or equal to 1) than the intervals t2 and t3, which are the second intervals for the second state.

[0082] Incidentally, when the viscosity of the reference ink is relatively low, if the interval t1 is set to (n×Tc) (n is a natural number), the oscillation of the pre-oscillation pulse PVP will be too strong, and the vibration caused by the pre-oscillation pulse PVP will not be able to attenuate, resulting in unstable ink ejection by the ejection pulse DP. Therefore, it is preferable to deviate the interval t1 from (n×Tc) and set the elements a1 to a3, b1 to b7, and c1 of the pre-oscillation pulse PVP and the ejection pulse DP so as to obtain the desired ink weight. For example, when the viscosity of the reference ink is relatively low, it is preferable to set the interval t1 to (n×Tc)×1.2 times, etc. On the other hand, when the viscosity of the reference ink is relatively high, the vibration of the ink is easily attenuated, so it is preferable to set the interval t1 to a value close to (n×Tc) (n is a natural number) and set the elements a1 to a3, b1 to b7, and c1 of the pre-oscillation pulse PVP and the ejection pulse DP so as to obtain the desired ink weight. When setting the interval t1 to (n±α)×Tc (n is a natural number) according to the liquid information acquired by the liquid information acquisition unit 200, α is made smaller, i.e., approached to 0 (zero), as the ink viscosity indicated by the acquired liquid information increases above the reference ink viscosity, and α is made closer to 0.5 as the ink viscosity indicated by the acquired liquid information decreases below the reference ink viscosity. This makes it possible to suppress variations in the weight of ink ejected from the nozzles 21, even if the ink viscosity fluctuates.

[0083] The acquisition of liquid information by the liquid information acquisition unit 200 is repeated at a predetermined timing. Here, the predetermined timing refers to the timing when the viscosity of the ink changes, and includes, for example, when the liquid is replaced, when the liquid is replaced with a liquid with different physical properties, when the environmental temperature changes by a predetermined amount, a predetermined time such as when printing starts, or regular times. The interval adjustment unit 201 adjusts the interval t1 of the reference drive waveform in conjunction with the predetermined timing at which the liquid information acquisition unit 200 acquires the liquid information, thereby preventing variations in the weight and flight speed of the ejected ink even when the viscosity of the ink changes.

[0084] (Other embodiments) Although one embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above.

[0085] In the above-described first embodiment, the interval between the pre-vibration pulse PVP and the ejection pulse DP adjusted by the interval adjusting unit 201 is the interval t1 between the start point of the first contraction element a3 of the pre-vibration pulse PVP and the start point of the second contraction element b3 of the ejection pulse DP, but is not particularly limited to this. The interval between the pre-vibration pulse PVP and the ejection pulse DP may be the interval between the start point of the first expansion element a1 of the pre-vibration pulse PVP and the start point of the second expansion element b1 of the ejection pulse DP, or may be the interval between the midpoint of the first contraction element a3 and the midpoint of the second contraction element b3.

[0086] Furthermore, in addition to adjusting the interval t1 between the pre-oscillation pulse PVP and the ejection pulse DP based on the liquid information acquired by the liquid information acquisition unit 200, the interval adjustment unit 201 may also adjust the potential change rate per unit time of the pre-oscillation pulse PVP, specifically the potential change rate per unit time of at least one of the first expansion element a1 and the first contraction element a3, or so-called gradient. For example, by reducing the potential change rate, or so-called gradient, for ink with low viscosity, it is possible to prevent ink from being ejected from the nozzle 21. Furthermore, by increasing the potential change rate, or so-called gradient, for ink with high viscosity, it is possible to increase the vibration of the meniscus of the nozzle 21.

[0087] Similarly, the interval adjustment unit 201 may adjust the potential change rate per unit time of the ejection pulse DP, specifically the potential change rate per unit time of at least one of the second expansion element b1 and the second contraction element b3, or so-called slope, in addition to adjusting the interval t1 between the pre-vibration pulse PVP and the ejection pulse DP based on the liquid information acquired by the liquid information acquisition unit 200. For example, by making the slope smaller for ink with low viscosity and making the slope larger for ink with high viscosity, it is possible to suppress variations in the weight and flight speed of the ejected ink even when the viscosity changes.

[0088] Furthermore, in addition to adjusting the interval t1 between the pre-oscillation pulse PVP and the ejection pulse DP based on the liquid information acquired by the liquid information acquisition unit 200, the interval adjustment unit 201 may also adjust the potential change width of the pre-oscillation pulse PVP, i.e., the potential difference Vh1 between the reference potential V0 and the first potential V1. For example, by reducing the potential difference Vh1 for low-viscosity ink, it is possible to prevent ink from being ejected from the nozzle 21. Furthermore, by increasing the potential difference Vh1 for high-viscosity ink, it is possible to increase the vibration of the meniscus of the nozzle 21.

[0089] Similarly, the interval adjustment unit 201 may adjust the potential change width of the ejection pulse DP, i.e., the potential difference Vh2 between the reference potential V0 and the second potential V2, in addition to adjusting the interval t1 between the pre-vibration pulse PVP and the ejection pulse DP based on the liquid information acquired by the liquid information acquisition unit 200. For example, by reducing the potential difference Vh2 for ink with low viscosity and increasing the potential difference Vh2 for ink with high viscosity, it is possible to suppress variations in the weight and flight speed of the ejected ink even when the viscosity changes.

[0090] 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. The viscosity of ink 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 weight of ink ejected from the nozzles 21. Such ink weight measurements can be made, for example, by capturing an image of the flying ink and processing the image, or by image processing the size of 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 weight of the 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.

[0091] Furthermore, the interval adjustment unit 201 adjusts the interval t1 between the pre-oscillation pulse PVP and the ejection pulse DP so that ejection characteristics such as the weight and flight speed of the ejected ink droplets do not vary even when the liquid information changes, but this is not particularly limited. For example, the interval between the pre-oscillation pulse PVP and the ejection pulse DP may be adjusted so that desired ejection characteristics are obtained according to the liquid information. In other words, the interval adjustment unit 201 may adjust the interval so that desired small dots, medium dots, large dots, etc. are ejected according to the liquid information.

[0092] In the first embodiment described above, the thin-film piezoelectric actuator 300, essentially the active portion 310, is used 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. The driving element can also be a so-called electrostatic 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.

[0093] 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.

[0094] 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.

[0095] (Addendum) From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0096] A preferred embodiment of a method for driving a liquid ejection device according to aspect 1 is a method for driving a liquid ejection device having an ejection unit including a nozzle that ejects liquid as droplets, a pressure chamber communicating 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 drive signal includes a pre-oscillation pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are not ejected from the nozzle, and an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle. The interval between the pre-oscillation pulse and the ejection pulse is set in response to acquired liquid information. This allows the weight of the droplets ejected from the nozzle to be increased by ejecting droplets using the pre-oscillation pulse and the ejection pulse. Furthermore, by adjusting the interval between the pre-oscillation pulse and the ejection pulse in response to the liquid information, variations in ejection characteristics such as the weight and flight speed of the droplets ejected from the nozzle can be suppressed even when the liquid information changes.

[0097] In Aspect 2, which is a specific example of Aspect 1, a storage unit is provided that stores reference drive waveform information corresponding to reference liquid information, and the interval between the pre-vibration pulse and the ejection pulse is set according to the difference between the acquired liquid information and the reference liquid information. This allows driving using an optimal drive waveform for the reference liquid, and by adjusting the interval according to the difference between the liquid information and the reference liquid information, a drive waveform suitable for the liquid information can be generated.

[0098] In Aspect 3, which is a specific example of Aspect 1, the first interval set according to the liquid information for the first state is set to a value closer to n times (n is a natural number greater than or equal to 1) the natural vibration period of the ejection unit than the second interval set according to the liquid information for the second state, and the viscosity of the liquid corresponding to the first state is higher than the viscosity of the liquid corresponding to the second state. This makes it possible to suppress variations in ejection characteristics such as the weight and flight speed of droplets ejected from the nozzle, even if the viscosity of the liquid changes.

[0099] In Aspect 4, which is a specific example of Aspect 1, the interval between the pre-vibration pulse and the ejection pulse is the interval between the start of contraction of the pre-vibration pulse and the start of contraction of the ejection pulse, thereby making it possible to reliably adjust the ejection characteristics, such as the weight and flight speed, of the droplets ejected from the nozzle.

[0100] In Aspect 5, which is a specific example of Aspect 1, the potential change width of the pre-oscillation pulse is smaller than the potential change width of the ejection pulse, and the potential change rate per unit time of the contraction element of the pre-oscillation pulse is smaller than the potential change rate per unit time of the contraction element of the ejection pulse. This makes it possible to reliably eject liquid from the nozzle by the ejection pulse while suppressing the pre-oscillation pulse from ejecting droplets from the nozzle.

[0101] In Aspect 6, which is a specific example of Aspect 1, the pre-vibration pulse has an expansion element, a sustain element, and a contraction element, and the total time of the expansion element and the sustain element is 0.45 to 0.55 times the natural vibration period of the ejection unit. This stabilizes the meniscus of the liquid in the nozzle and allows it to vibrate widely.

[0102] In Aspect 7, which is a specific example of Aspect 1, the potential change rate per unit time of the pre-vibration pulse is changed in accordance with the acquired liquid information. This makes it possible to prevent droplets from being ejected from the nozzle in accordance with the liquid information, and to greatly vibrate the meniscus of the nozzle.

[0103] In Aspect 8, which is a specific example of Aspect 1, the potential change width of the pre-vibration pulse is changed in accordance with the acquired liquid information. This makes it possible to prevent droplets from being ejected from the nozzle in accordance with the liquid information, and to greatly vibrate the meniscus of the nozzle.

[0104] In Aspect 9, 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.

[0105] In Aspect 10, which is a specific example of Aspect 1, the liquid information includes temperature information corresponding to the temperature of the liquid. Accordingly, 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.

[0106] In an eleventh aspect that is a specific example of the first aspect, the liquid information includes the liquid information input by a user.

[0107] A preferred embodiment of a liquid ejection device according to aspect 12 includes a nozzle that ejects liquid as droplets, a pressure chamber communicating with the nozzle, and an ejection unit including a drive element that applies pressure fluctuations to the liquid in the pressure chamber. The ejection unit also includes a control unit that acquires liquid information about the liquid and supplies a drive signal to the drive element. The drive signal includes a pre-oscillation pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are not ejected from the nozzle, and an ejection pulse that applies pressure fluctuations to the liquid in the pressure chamber so that droplets are ejected from the nozzle. The control unit sets the interval between the pre-oscillation pulse and the ejection pulse in accordance with the acquired liquid information. This allows the weight of droplets ejected from the nozzle to be increased by ejecting droplets using the pre-oscillation pulse and the ejection pulse. Furthermore, by adjusting the interval between the pre-oscillation pulse and the ejection pulse in accordance with the liquid information, variations in ejection characteristics, such as the weight and flight speed of droplets ejected from the nozzle, can be suppressed even when the liquid information changes. [Explanation of symbols]

[0108] COM...drive signal, DP...ejection pulse, PVP...pre-vibration pulse, S...medium, T...drive period, t1, t2, t3...interval, Tc...natural vibration period, 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 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...gap adjustment unit, 202...memory 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 is a pre-vibration pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that droplets are not ejected from the nozzle; an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that droplets are ejected from the nozzle; and setting an interval between the pre-vibration pulse and the ejection pulse in accordance with the acquired liquid information; A method for driving a liquid ejection device.

2. a storage unit that stores reference drive waveform information corresponding to the reference liquid information; setting an interval between the pre-vibration pulse and the ejection pulse in accordance with a difference between the acquired liquid information and the reference liquid information; 2. The method for driving a liquid ejection apparatus according to claim 1.

3. the first interval set in accordance with the liquid information in the first state is set to a value closer to n times (n is a natural number equal to or greater than 1) the natural vibration period of the ejection portion than the second interval set in accordance with the liquid information in the second state; The viscosity of the liquid corresponding to the first state is higher than the viscosity of the liquid corresponding to the second state.

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

4. the interval between the pre-vibration pulse and the ejection pulse is the interval between the start of contraction of the pre-vibration pulse and the start of contraction of the ejection pulse; 2. The method for driving a liquid ejection apparatus according to claim 1.

5. a potential change width of the pre-vibration pulse is smaller than a potential change width of the ejection pulse; a potential change rate per unit time of the contraction element of the pre-vibration pulse is smaller than a potential change rate per unit time of the contraction element of the ejection pulse; 2. The method for driving a liquid ejection apparatus according to claim 1.

6. the pre-vibration pulse has an expansion component, a maintenance component, and a contraction component; The total time of the expansion element and the maintenance element is 0.45 times or more and 0.55 times or less of the natural vibration period of the discharge portion.

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

7. changing a rate of change in potential per unit time of the pre-vibration pulse in accordance with the acquired liquid information; 2. The method for driving a liquid ejection apparatus according to claim 1.

8. changing a potential change width of the pre-vibration pulse in accordance with the acquired liquid information; 2. The method for driving a liquid ejection apparatus according to claim 1.

9. the liquid information includes residual vibration information corresponding to residual vibration of the liquid in the pressure chamber.

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

10. the liquid information includes temperature information corresponding to a temperature of the liquid; 2. The method for driving a liquid ejection apparatus according to claim 1.

11. The liquid information includes the liquid information input by a user.

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

12. 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 is a pre-vibration pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that droplets are not ejected from the nozzle; an ejection pulse that applies a pressure fluctuation to the liquid in the pressure chamber so that droplets are ejected from the nozzle; and the control unit sets an interval between the pre-vibration pulse and the ejection pulse in accordance with the acquired liquid information. A liquid ejection device characterized by:

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