Liquid dispensing device

Abstract

This reduces fluctuations in discharge volume caused by increased liquid viscosity across a wider viscosity range, while also suppressing unstable discharge. [Solution] The liquid dispensing device has a drive signal which includes a dispensing pulse that causes a droplet to be dispensed from a nozzle, and the dispensing pulse includes a first contraction element which changes its potential by a first potential change amount to contract a pressure chamber, a first contraction maintenance element connected to the end of the first contraction element which maintains the end potential of the first contraction element, and a second contraction element connected to the end of the first contraction maintenance element which changes its potential by a second potential change amount to contract a pressure chamber, wherein when the viscosity indicated by the viscosity information is a first viscosity, the ratio of the first potential change amount to the second potential change amount is a first value, and when the viscosity indicated by the viscosity information is a second viscosity which is higher than the first viscosity, the ratio of the first potential change amount to the second potential change amount is a second value which is smaller than the first value.

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection device.

Background Art

[0002] In a liquid ejection device typified by a piezoelectric inkjet printer, by supplying a drive signal to a piezoelectric element to cause pressure fluctuations in the liquid in the pressure chamber, the liquid is ejected from a nozzle communicating with the pressure chamber. In such a liquid ejection device, in order to suppress a decrease in ejection characteristics due to a change in the viscosity of the liquid, the drive signal may be corrected according to the viscosity of the liquid. For example, Patent Document 1 discloses a liquid ejection device that adjusts the amount of potential change of a drive signal based on the detection result of a temperature sensor that detects the temperature of the liquid in order to suppress a decrease in ejection characteristics due to a change in viscosity accompanying a change in the temperature of the liquid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, since only the amount of potential change of the drive signal is adjusted, when the viscosity change width of the liquid becomes larger than a predetermined value, it may be difficult to maintain the ejection characteristics constant.

Means for Solving the Problems

[0005] To solve the above problems, a liquid dispensing device according to a preferred embodiment of the present disclosure comprises a dispensing unit having a nozzle for dispensing liquid, a pressure chamber communicating with the nozzle, and a piezoelectric element that is driven to cause pressure fluctuations in the liquid in the pressure chamber in response to a supplied drive signal; a drive signal generation circuit for generating the drive signal; an acquisition unit for acquiring viscosity information indicating the viscosity of the liquid; and a control unit for controlling the operation of the drive signal generation circuit, wherein the drive signal includes a dispensing pulse for dispensing droplets from the nozzle, and the dispensing pulse is a first potential change amount that causes the pressure chamber to contract. The pressure chamber comprises a contraction element, a first contraction maintenance element connected to the end of the first contraction element and maintaining the terminal potential of the first contraction element, and a second contraction element connected to the end of the first contraction maintenance element and changing its potential by a second potential change amount to contract the pressure chamber, wherein when the viscosity indicated by the viscosity information is a first viscosity, the ratio of the first potential change amount to the second potential change amount is a first value, and when the viscosity indicated by the viscosity information is a second viscosity higher than the first viscosity, the ratio of the first potential change amount to the second potential change amount is a second value smaller than the first value. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram showing an example of the configuration of a liquid dispensing device according to the first embodiment. [Figure 2] This block diagram shows the electrical configuration of the liquid dispensing device according to the first embodiment. [Figure 3] This is a cross-section of the head. [Figure 4] This is a diagram showing an example of a drive circuit configuration. [Figure 5] This is an explanatory diagram of the discharge pulse and test pulse included in the drive signal. [Figure 6] This is a flowchart showing the driving method of a liquid dispensing device according to the first embodiment. [Figure 7] This figure shows the relationship between the viscosity of the liquid and the ratio of the potential change in the discharge pulse PD. [Figure 8]This is an explanatory diagram of the discharge pulse when the viscosity indicated by the viscosity information is the first viscosity. [Figure 9] This is an explanatory diagram of the discharge pulse when the viscosity indicated by the viscosity information is the second viscosity. [Figure 10] This is an explanatory diagram of the discharge pulse when the viscosity indicated by the viscosity information is the third viscosity. [Figure 11] This is an explanatory diagram illustrating another example of a discharge pulse when the viscosity indicated by the viscosity information is the third viscosity. [Figure 12] This diagram illustrates the discharge pulse in the second embodiment when the viscosity indicated by the viscosity information is the first viscosity. [Figure 13] This diagram illustrates the discharge pulse in the second embodiment when the viscosity indicated by the viscosity information is a second viscosity. [Figure 14] This diagram illustrates the discharge pulse in the second embodiment when the viscosity indicated by the viscosity information is a third viscosity. [Figure 15] This diagram illustrates another example of a discharge pulse in the second embodiment, where the viscosity indicated by the viscosity information is a third viscosity. [Modes for carrying out the invention]

[0007] Preferred embodiments of the present disclosure will be described below with reference to the attached drawings. Note that the dimensions and scale of parts in the drawings may differ from actual dimensions as appropriate, and some parts are shown schematically for ease of understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise stated in the following description.

[0008] The following explanation uses the intersecting X, Y, and Z axes as appropriate for the purpose of identifying position or direction. In the following, one direction along the X axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, opposite directions along the Y axis are the Y1 and Y2 directions. Also, opposite directions along the Z axis are the Z1 and Z2 directions.

[0009] Here, typically, the Z-axis is the vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Also, the X-axis, Y-axis, and Z-axis typically intersect orthogonally with each other, but are not limited thereto, and for example, they may intersect at an angle within the range of 80° or more and 100° or less.

[0010] A: First Embodiment A1: Overall Configuration of Liquid Discharge Device FIG. 1 is a schematic diagram showing a configuration example of a liquid discharge device 100 according to the first embodiment. The liquid discharge device 100 is an inkjet printing device that discharges ink, which is an example of "liquid", as droplets toward a medium M. The medium M is, for example, printing paper. Note that the medium M is not limited to printing paper, and may be a printing target of any material such as a resin film or fabric.

[0011] As shown in FIG. 1, the liquid discharge device 100 includes a liquid container 110, a control module 120, a conveyance mechanism 130, a movement mechanism 140, a head module 150, a temperature sensor 160, and an input device 170.

[0012] The liquid container 110 stores ink. Specific examples of the liquid container 110 include a cartridge that is detachable from the liquid discharge device 100, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. Note that the type of ink stored in the liquid container 110 is arbitrary.

[0013] The control module 120 controls the operations of each element of the liquid discharge device 100. Details of the control module 120 will be described later based on FIG. 2.

[0014] The conveyance mechanism 130 conveys the medium M along the Y-axis under the control of the control module 120.

[0015] Under the control of the control module 120, the moving mechanism 140 reciprocates the head module 150 along the X-axis. The moving mechanism 140 includes a substantially box-shaped carrier 141, referred to as a carriage, that houses the head module 150, and an endless conveyor belt 142 to which the carrier 141 is fixed. Note that the number of head modules 150 mounted on the carrier 141 is not limited to one, and a plurality of them may be provided. Further, in addition to the head module 150, the aforementioned liquid container 110 may be mounted on the carrier 141.

[0016] Under the control of the control module 120, the head module 150 discharges ink supplied from the liquid container 110 from each of a plurality of nozzles onto the medium M. By performing this discharge in parallel with the conveyance of the medium M by the conveyance mechanism 130 and the reciprocating movement of the head module 150 by the moving mechanism 140, an image formed by the ink is formed on the surface of the medium M.

[0017] The temperature sensor 160 detects temperature. More specifically, the temperature sensor 160 is, for example, a resistance temperature sensor such as a linear resistor or a thermistor, and detects the temperature of the ink in the pressure chamber C described later. In the example shown in FIG. 1, the temperature sensor 160 is installed in the head module 150. Note that the installation position of the temperature sensor 160 is not limited to the example shown in FIG. 1, and may be a position where the temperature of the ink in the pressure chamber C described later can be directly detected, or a location where a detection result capable of estimating the temperature of the ink in the pressure chamber C described later can be obtained, and is not particularly limited. Further, the temperature sensor 160 is not limited to a resistance temperature sensor, and an optical temperature sensor may be used.

[0018] The input device 170 is a device that receives input from the user and outputs input information DY based on the user's input. For example, the input device 170 includes an operation panel or a remote control receiver. The operation panel is, for example, provided on the outer casing of the liquid dispensing device 100 and outputs input information DY as an electrical signal based on user operation. The remote control receiver receives, for example, an infrared signal from a remote control, decodes the infrared signal, and outputs input information DY as an electrical signal based on user operation to the remote control. The input device 170 may be provided as needed or omitted.

[0019] A2: Electrical configuration of the liquid dispensing device Figure 2 is a block diagram showing the electrical configuration of the liquid dispensing device 100 according to the first embodiment. As shown in Figure 2, the head module 150 includes a head 151, a drive circuit 152, and a detection circuit 153.

[0020] The head 151 is equipped with a plurality of ejection sections 50. Each ejection section 50 is a structure for ejecting ink and has a nozzle N, a pressure chamber C, and a piezoelectric element 56, as will be described later with reference to Figure 3.

[0021] The print head 151 has M piezoelectric elements 56_1 to 56_M, and ink is ejected from the nozzle N described later by driving the piezoelectric elements 56_1 to 56_M. M is a natural number greater than or equal to 2. In the following, when the piezoelectric elements 56_1 to 56_M are not distinguished, they may each be referred to as piezoelectric element 56. Also, in the following, the correspondence between the M other components corresponding to piezoelectric elements 56 in the liquid ejection device 100 and piezoelectric elements 56_1 to 56_M may be indicated using the subscripts "_1 to _M" or "[1] to [M]".

[0022] Each piezoelectric element 56 is driven by the inverse piezoelectric effect upon receiving the supply drive signal Vin. Each piezoelectric element 56 also outputs an output signal Vout through the piezoelectric effect. Details of the head 151 will be explained later with reference to Figure 3.

[0023] In the example shown in Figure 2, the head module 150 has one head 151, but this is not limited to this; the head module 150 may have two or more heads 151.

[0024] The drive circuit 152 drives the piezoelectric elements 56 under the control of the control module 120. Specifically, under the control of the control module 120, the drive circuit 152 switches whether or not to supply the drive signal Com output from the control module 120 as a supply drive signal Vin to each of the multiple piezoelectric elements 56 of the head 151. In this embodiment, under the control of the control module 120, the drive circuit 152 also switches whether or not to supply the electromotive force in each of the multiple piezoelectric elements 56 of the head 151 as an output signal Vout to the detection circuit 153. Details of the drive circuit 152 will be explained later with reference to Figure 4.

[0025] The detection circuit 153 detects residual vibrations generated in the pressure chamber C when the piezoelectric element 56 is supplied with the inspection pulse PD2 described later. Here, the detection circuit 153 generates vibration information NVT indicating the residual vibrations based on the output signal Vout, which is an electrical signal generated by each piezoelectric element 56. For example, the detection circuit 153 generates vibration information NVT by amplified the output signal Vout after noise reduction. Residual vibrations are vibrations that remain in the pressure chamber C after the piezoelectric element 56 is driven, and they vibrate at the natural vibration period (Tc) of the discharge section 50. As described above, the detection circuit 153 acquires vibration information NVT as an electrical signal indicating the residual vibrations of the liquid in the pressure chamber C after the piezoelectric element 56 has caused pressure fluctuations in the liquid in the pressure chamber C.

[0026] As shown in Figure 2, the control module 120 includes a control circuit 121, a memory circuit 122, a power supply circuit 123, and a drive signal generation circuit 124.

[0027] The control circuit 121 has the function of controlling the operation of each part of the liquid dispensing device 100, and the function of processing various data.

[0028] The control circuit 121 includes, for example, one or more processors such as CPUs (Central Processing Units). The control circuit 121 may also include a programmable logic device such as an FPGA (field-programmable gate array) instead of a CPU, or in addition to a CPU. Furthermore, if the control circuit 121 is composed of multiple processors, for example, the operation control of the drive circuit 152 and the operation control of the detection circuit 153 may be performed by separate processors. Also, if the control circuit 121 is composed of multiple processors, these multiple processors may be mounted on different boards or the like.

[0029] The memory circuit 122 stores various programs executed by the control circuit 121 and various data such as print data Img processed by the control circuit 121. The memory circuit 122 includes, for example, one or both of semiconductor memories: volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM). The print data Img is supplied from an external device 200 such as a personal computer or digital camera. Note that part or all of the memory circuit 122 may be configured as part of the control circuit 121.

[0030] The memory circuit 122 stores vibration information NVT, temperature information DT, input information DY, and viscosity information DV.

[0031] The vibration information NVT is information indicating residual vibration detected by the detection circuit 153 when the inspection pulse PD2, described later, is supplied to the piezoelectric element 56.

[0032] Temperature information DT indicates the temperature detected by the temperature sensor 160. The temperature indicated by temperature information DT is the temperature of the ink in the pressure chamber C, described later, or a temperature corresponding to that temperature.

[0033] The input information DY is information indicating the user's input result to the input device 170 as a result of reception by the reception unit 121c described later. The input information DY is information related to the viscosity of the ink in the ejection unit 50, and includes information such as ink viscosity characteristics and ink type.

[0034] Viscosity information DV indicates the viscosity of the liquid. The viscosity indicated by viscosity information DV is the viscosity of the ink in pressure chamber C, which will be described later.

[0035] The power supply circuit 123 receives power from a commercial power source (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the liquid dispensing device 100 as appropriate. For example, the power supply circuit 123 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the head module 150. The power supply potential VHV is supplied to the drive signal generation circuit 124.

[0036] The drive signal generation circuit 124 is a circuit that generates a drive signal Com for driving each piezoelectric element 56. Specifically, the drive signal generation circuit 124 includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 124, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 121 from a digital signal to an analog signal, and the amplification circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 123 to generate the drive signal Com. Here, among the waveforms included in the drive signal Com, the signal of the waveform actually supplied to the piezoelectric element 56 (discharge pulse PD1 or test pulse PD2 described later) is the aforementioned supply drive signal Vin. The waveform specification signal dCom is a digital signal for defining the waveform of the drive signal Com.

[0037] In the control module 120 described above, the control circuit 121 controls the operation of each part of the liquid dispensing device 100 by executing a program stored in the memory circuit 122. Here, the control circuit 121 generates control signals Sk1 and Sk2, a control signal SI, and a waveform specification signal dCom as signals for controlling the operation of each part of the liquid dispensing device 100 by executing the program.

[0038] Control signal Sk2 is a signal for controlling the drive of the transport mechanism 130. Control signal Sk1 is a signal for controlling the drive of the moving mechanism 140. Control signal SI is a digital signal for specifying the operating state of the piezoelectric element 56. Control signal SI may also include a timing signal for defining the driving timing of the piezoelectric element 56. This timing signal is generated, for example, based on the output of the encoder that detects the position of the transport body 141.

[0039] Furthermore, the control circuit 121 functions as an acquisition unit 121a, a control unit 121b, and a receiving unit 121c by executing a program stored in the memory circuit 122. Thus, the liquid dispensing device 100 includes an acquisition unit 121a, a control unit 121b, and a receiving unit 121c.

[0040] The acquisition unit 121a acquires viscosity information DV. For example, the acquisition unit 121a acquires viscosity information DV based on at least one of vibration information NVT, temperature information DT, and input information DY. The acquired viscosity information DV is stored in the memory circuit 122.

[0041] To explain in more detail, the higher the viscosity of the ink in the pressure chamber C described later, the higher the attenuation rate of the residual vibration amplitude. Therefore, the relationship between the viscosity of the ink and the attenuation of the residual vibration amplitude is obtained in advance, and the acquisition unit 121a acquires viscosity information DV based on the attenuation state of the residual vibration amplitude indicated by the vibration information NVT and this relationship. In this way, the acquisition unit 121a acquires viscosity information DV based on the electrical signal from the detection circuit 153, i.e., the vibration information NVT. This makes it possible to acquire viscosity information DV without adding elements such as a temperature sensor 160. Alternatively, viscosity information DV can be acquired even when using ink with unknown characteristics.

[0042] Furthermore, the viscosity of the ink decreases as the temperature of the ink in the pressure chamber C, described later, increases. Therefore, the relationship between the viscosity of the ink and its temperature is acquired in advance, and the acquisition unit 121a acquires viscosity information DV based on the temperature indicated by the temperature information DT and this relationship. In this way, the acquisition unit 121a acquires viscosity information DV based on the temperature detected by the temperature sensor 160. This makes it possible to directly acquire viscosity information DV that shows the change in viscosity due to the temperature change of the liquid. Here, the relationship between the viscosity of the ink and the damping rate of the amplitude of residual vibration changes depending on the temperature of the ink. Therefore, when acquiring viscosity information DV based on vibration information NVT, the acquisition unit 121a can also acquire a correlation between viscosity information DV and temperature information DT based on viscosity information DV and temperature information DT. While the same ink is used, the acquired correlation between viscosity information DV and temperature information DT can be referred to, and viscosity information DV can be acquired from the detected temperature information DT.

[0043] Furthermore, the viscosity of the ink varies depending on the type of ink. Therefore, the acquisition unit 121a acquires viscosity information DV based on the reception result of the reception unit 121c, i.e., the input information DY. This makes it possible to acquire viscosity information DV corresponding to the input information DY regarding the type of ink to be used, which is entered by the user. Here, the input information DY may also be viscosity information DV, and the acquisition unit 121a may directly acquire viscosity information DV based on the input information DY. Alternatively, the acquisition unit 121a may acquire or correct the relationship between the viscosity of the ink and the natural vibration period of the residual vibration based on the input information DY, and then acquire viscosity information DV based on vibration information NVT. Furthermore, the acquisition unit 121a may acquire or correct the relationship between the viscosity of the ink and the temperature based on the information indicated by the input information DY, and then acquire viscosity information DV based on temperature information DT.

[0044] The control unit 121b controls the operation of the drive signal generation circuit 124. Here, the control unit 121b corrects the discharge pulse PD1, which will be described later, based on the viscosity information DV.

[0045] The reception unit 121c receives input from the user. In this embodiment, the reception unit 121c receives input information DY, which indicates the input result of the input device 170 as performed by the user.

[0046] A3: Head Figure 3 is a cross-sectional view of the print head 151. As shown in Figure 3, the print head 151 has a plurality of nozzles N for ejecting ink. These plurality of nozzles N are divided into a first row L1 and a second row L2, which are spaced apart from each other in the direction along the X-axis. Each of the first row L1 and the second row L2 is a collection of a plurality of nozzles N arranged linearly in the direction along the Y-axis.

[0047] The head 151 has a configuration that is approximately symmetrical with respect to the X-axis. However, the positions of the multiple nozzles N in the first row L1 and the multiple nozzles N in the second row L2 along the Y-axis may coincide or differ. Figure 3 illustrates a configuration in which the positions of the multiple nozzles N in the first row L1 and the multiple nozzles N in the second row L2 along the Y-axis coincide.

[0048] As shown in Figure 3, the head 151 includes a flow channel substrate 51, a pressure chamber substrate 52, a nozzle plate 53, a vibration absorber 54, a diaphragm 55, a plurality of piezoelectric elements 56, a protective substrate 57, a case 58, and a wiring substrate 59.

[0049] The flow channel substrate 51 and the pressure chamber substrate 52 are stacked in this order in the Z1 direction, forming a flow channel for supplying ink to multiple nozzles N. A diaphragm 55, multiple piezoelectric elements 56, a protective substrate 57, a case 58, a wiring board 59, and a drive circuit 152 are installed in the region located in the Z1 direction from the stack consisting of the flow channel substrate 51 and the pressure chamber substrate 52. On the other hand, a nozzle plate 53 and a vibration absorber 54 are installed in the region located in the Z2 direction from the stack. Each element of the head 151 is generally a plate-shaped member that is elongated in the Y direction, and is joined to each other, for example, by adhesive. The elements of the head 151 will be described in order below.

[0050] The nozzle plate 53 is a plate-shaped member provided with a plurality of nozzles N in the first row L1 and the second row L2, respectively. Each of the plurality of nozzles N is a through-hole through which ink passes and ejects ink. Here, the surface of the nozzle plate 53 facing the Z2 direction is the nozzle surface FN. The nozzle plate 53 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, such as dry etching or wet etching. However, other known methods and materials may be used in the manufacture of the nozzle plate 53 as appropriate. In addition, the cross-sectional shape of the nozzle is typically circular, but is not limited to this, and may be non-circular, such as polygonal or elliptical.

[0051] The flow channel substrate 51 is provided with a space R1, a plurality of supply channels Ra, and a plurality of communication channels Na for each of the first row L1 and the second row L2. Space R1 is a long opening extending in the direction along the Y axis when viewed in a plan view along the Z axis. Each of the supply channels Ra and communication channels Na is a through hole formed for each nozzle N. Each supply channel Ra communicates with space R1.

[0052] The pressure chamber substrate 52 is a plate-shaped member in which multiple pressure chambers C, referred to as cavities, are provided for each of the first row L1 and the second row L2. The multiple pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed for each nozzle N and is a long, elongated space that extends in a direction along the X axis in a plan view.

[0053] The channel substrate 51 and the pressure chamber substrate 52 are manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, similar to the nozzle plate 53 described above. However, other known methods and materials may be used as appropriate for the manufacture of the channel substrate 51 and the pressure chamber substrate 52.

[0054] The pressure chamber C is located between the flow channel substrate 51 and the diaphragm 55. For each of the first row L1 and the second row L2, multiple pressure chambers C are arranged in a direction along the Y axis. The pressure chamber C also communicates with the communication channel Na and the supply channel Ra, respectively. Therefore, the pressure chamber C communicates with the nozzle N via the communication channel Na and with space R1 via the supply channel Ra.

[0055] A diaphragm 55 is positioned on the surface of the pressure chamber substrate 52 facing the Z1 direction. The diaphragm 55 is an elastically vibrating plate-shaped member. The diaphragm 55 has, for example, an elastic film made of silicon oxide (SiO2) and an insulating film made of zirconium oxide (ZrO2), which are stacked in this order in the Z1 direction. The elastic film is formed, for example, by thermal oxidation of one surface of a silicon single crystal substrate. The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Note that the diaphragm 55 is not limited to the stacked structure of the elastic film and insulating film described above, and may be composed of a single layer or three or more layers.

[0056] On the surface of the diaphragm 55 facing the Z1 direction, multiple piezoelectric elements 56 corresponding to nozzles N are arranged for each of the first row L1 and second row L2. Each piezoelectric element 56 is driven in response to a supplied drive signal Com so that pressure fluctuations occur in the ink within the pressure chamber C. Each piezoelectric element 56 is elongated in a direction along the X-axis in a plan view. Multiple piezoelectric elements 56 are arranged along the Y-axis to correspond to multiple pressure chambers C. The piezoelectric elements 56 overlap the pressure chambers C in a plan view.

[0057] Each piezoelectric element 56, although not shown in the figures, has a first electrode, a piezoelectric layer, and a second electrode, and these are stacked in this order in the Z1 direction. One of the first and second electrodes is an individual electrode that is spaced apart from each other for each piezoelectric element 56, and a drive signal Com is supplied to this electrode. The other electrode is a strip-shaped common electrode that extends in the direction along the Y axis so as to be continuous across the plurality of piezoelectric elements 56, and a constant potential offset potential VBS is supplied to this other electrode, for example. Examples of metallic materials for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), and one of these can be used alone or two or more can be used in combination in the form of an alloy or stacking. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3) and, for example, forms a strip that extends along the Y-axis so as to be continuous across multiple piezoelectric elements 56. Here, through holes extending along the X-axis are provided in the piezoelectric layer in regions corresponding to the gaps between adjacent pressure chambers C in a plan view. When the diaphragm 55 vibrates in conjunction with the deformation of the piezoelectric elements 56, the pressure in the pressure chamber C fluctuates, causing ink to be ejected from the nozzle N. Note that the piezoelectric layer may be provided individually for each piezoelectric element 56.

[0058] The protective substrate 57 is a plate-shaped member installed on the surface of the diaphragm 55 facing the Z1 direction, protecting the multiple piezoelectric elements 56 and reinforcing the mechanical strength of the diaphragm 55. Here, the multiple piezoelectric elements 56 are housed in the space S between the protective substrate 57 and the diaphragm 55. The protective substrate 57 is made of, for example, a resin material.

[0059] Case 58 is a case for storing ink supplied to multiple pressure chambers C. Case 58 is made of, for example, a resin material. Each of the first row L1 and the second row L2 of Case 58 is provided with a space R2. Space R2 is a space that communicates with the aforementioned space R1 and, together with space R1, functions as a reservoir R for storing ink supplied to the multiple pressure chambers C. Case 58 is provided with an inlet IO for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chamber C via each supply channel Ra.

[0060] The vibration absorber 54, also called the compliance substrate, is a flexible resin film that forms the wall surface of the reservoir R and absorbs pressure fluctuations of the ink in the reservoir R. The vibration absorber 54 may also be a thin, flexible metal plate. The surface of the vibration absorber 54 facing the Z1 direction is joined to the flow channel substrate 51 by adhesive or the like.

[0061] The wiring board 59 is mounted on the surface of the diaphragm 55 facing the Z1 direction and is a mounting component for electrically connecting the control module 120 and the head 151. The wiring board 59 is a flexible wiring board such as COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable). The aforementioned drive circuit 152 is mounted on the wiring board 59 in this embodiment. The wiring board 59 may also be a rigid board. In this case, the drive circuit 152 is mounted on the rigid board or on a flexible board connected to the rigid board.

[0062] A4: Details of the drive circuit Figure 4 shows an example configuration of the drive circuit 152. As shown in Figure 4, the drive circuit 152 is connected to wirings LHd, LHa, and LHs. Wiring LHd is a power supply line to which the offset potential VBS is supplied. Wiring LHa is a signal line that transmits the drive signal Com. Wiring LHs is a signal line that transmits the output signal Vout.

[0063] The drive circuit 152 includes M switches SWa (SWa[1]] to SWa[M]), M switches SWs (SWs[1]] to SWs[M]), and a connection state specification circuit 152a that specifies the connection state of these switches.

[0064] Switch SWa[m] is a switch that toggles between conduction (on) and non-conduction (off) between the wiring LHa for the transmission of the drive signal Com and the piezoelectric element 56[m], where m is a natural number between 1 and M. Switch SWs[m] is a switch that toggles between conduction (on) and non-conduction (off) between the wiring LHs for the transmission of the output signal Vout and the piezoelectric element 56[m]. Each of these switches is, for example, a transmission gate.

[0065] The connection status specification circuit 152a generates connection status specification signals SLa[1] to SLa[M] that specify the on / off state of switches SWa[1] to SWa[M], and connection status specification signals SLs[1] to SLs[M] that specify the on / off state of switches SWs[1] to SWs[M], based on the control signal SI.

[0066] As described above, the on / off state of the switch SWa[m] is switched according to the connection state specification signal SLa[m] generated. For example, the switch SWa[m] is ON when the connection state specification signal SLa[m] is high level and OFF when it is low level. As described above, the drive circuit 152 supplies a part or all of the waveform included in the drive signal Com as a supply drive signal Vin to one or more piezoelectric elements 56 selected from piezoelectric elements 56_1 to 56_M.

[0067] Furthermore, the on / off state of the switch SWs[m] is switched according to the connection status specification signal SLs[m]. For example, the switch SWs[m] is turned on when the connection status specification signal SLs[m] is high level and turned off when it is low level. As described above, the drive circuit 152 supplies the output signal Vout from one or more piezoelectric elements 56 selected from piezoelectric elements 56_1 to 56_M to the detection circuit 153.

[0068] A5: Drive signal Figure 5 is an explanatory diagram of the discharge pulse PD1 and the inspection pulse PD2 included in the drive signal Com. As shown in Figure 5, the drive signal Com includes the discharge pulse PD1 and the inspection pulse PD2 and is repeated in a unit period Tu. The unit period Tu is divided into a preceding period Tu1 which includes the discharge pulse PD1 and a succeeding period Tu2 which includes the inspection pulse PD2. In the example shown in Figure 5, the lengths of period Tu1 and period Tu2 are equal. In this embodiment, period Tu1 and period Tu2 are used as control periods for switching switches SWa[m] and SWs[m], respectively.

[0069] Note that the switching of switches SWa[m] and SWs[m] may be performed during a control period shorter than period Tu1 or period Tu2. Also, the lengths of period Tu1 and period Tu2 may be different from each other. Furthermore, although not shown in the diagram, the switching of switches SWa[2]~SWa[M] and switches SWs[2]~SWs[M] is also performed with period Tu1 and period Tu2 as the control periods, respectively.

[0070] The ejection pulse PD1 is a pulse that causes ink to be ejected from the nozzle N as a droplet. The ejection pulse PD1 is supplied to the piezoelectric element 56, which causes pressure fluctuations in the ink in the pressure chamber C to be ejected from the nozzle N. In the example shown in Figure 5, the ejection pulse PD1 has a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE in this order.

[0071] The first contraction element ES1 undergoes a potential change by a first potential change V1 to contract the pressure chamber C. The first contraction maintenance element ER1 is connected to the end of the first contraction element ES1 and maintains the terminal potential of the first contraction element ES1. The second contraction element ES2 is connected to the end of the first contraction maintenance element ER1 and undergoes a potential change by a second potential change V2 to contract the pressure chamber C. The second contraction maintenance element ER2 is connected to the end of the second contraction element ES2 and maintains the terminal potential of the second contraction element ES2. The expansion element EE undergoes a potential change to expand the pressure chamber C.

[0072] Here, the starting potential of the first contraction element ES1 and the ending potential of the expansion element EE are both reference potentials V0.

[0073] The inspection pulse PD2 is a pulse for detecting residual vibration. By supplying the inspection pulse PD2 to the piezoelectric element 56, pressure fluctuations are generated in the ink in the pressure chamber C without ejecting ink from the nozzle N. In the example shown in Figure 5, the inspection pulse PD2 has an expansion element Ea, an expansion maintenance element Eb, and a contraction element Ec in that order.

[0074] The expansion element Ea changes its potential by a potential change amount VE to expand the pressure chamber C. The expansion maintenance element Eb is connected to the end of the expansion element Ea and maintains the terminal potential of the expansion element Ea. The contraction element Ec changes its potential by a potential change amount VE to contract the pressure chamber C. In this way, the potential of the inspection pulse PD2 drops to a potential lower than the reference potential V0, maintains that potential for a predetermined time, and then returns to the reference potential V0. Note that the waveform of the inspection pulse PD2 is arbitrary and not limited to the example shown in Figure 5, as long as it can cause pressure fluctuations in the ink in the pressure chamber C without ejecting ink from the nozzle N.

[0075] A6: Driving method of liquid dispensing device Figure 6 is a flowchart illustrating the driving method of the liquid dispensing device 100 according to the first embodiment. As shown in Figure 6, the driving method includes steps S1 to S5 in that order. Note that the order of steps S1 to S3 is arbitrary and not limited to the illustrated example, and can be performed as long as it precedes step S4.

[0076] In step S1, the control circuit 121, which functions as a reception unit 121c, receives input information DY. More specifically, in step S1, the reception unit 121c receives the user's input result to the input device 170 as input information DY. The received input information DY is stored in the memory circuit 122.

[0077] After step S1, in step S2, the control circuit 121 acquires temperature information DT. More specifically, in step S2, the control circuit 121 acquires the detection result of the temperature sensor 160 as temperature information DT. The acquired temperature information DT is stored in the memory circuit 122. As mentioned above, step S2 may be performed before step S4, or before step S1.

[0078] After step S2, in step S3, the control circuit 121 acquires vibration information NVT. More specifically, in step S3, the control circuit 121 acquires vibration information NVT from the detection circuit 153, which indicates the residual vibration of the ink in the pressure chamber C after a pressure fluctuation has been introduced to the ink in the pressure chamber C by supplying a test pulse PD2 to the piezoelectric element 56. The acquired vibration information NVT is stored in the memory circuit 122. As mentioned above, step S3 may be performed before step S4, or before step S1 or step S2.

[0079] After steps S1 to S3 described above, in step S4, the control circuit 121, which functions as an acquisition unit 121a, acquires viscosity information DV based on the input information DY, temperature information DT, and vibration information NVT. The acquired viscosity information DV is stored in the memory circuit 122.

[0080] After step S4, in step S5, the control circuit 121, which functions as the control unit 121b, corrects the discharge pulse PD1 based on the viscosity information DV. This correction will be described in detail below.

[0081] A7: Correction of discharge pulse Figure 7 shows the relationship between the viscosity of the liquid and the ratio of the potential change of the discharge pulse PD. In Figure 7, the relationship between the viscosity of the ink and the ratio of the first potential change V1 to the second potential change V2 (V1 / V2), and the relationship between the viscosity of the ink and the ratio of the third potential change V3 to the second potential change V2 (V3 / V2), are shown when the actual discharge amount is the target discharge amount α, β, and γ. Here, the sum of the first potential change V1 and the second potential change V2 is constant. The third potential change V3 is the potential change of the first expansion element EE1, which will be described later and shown in Figure 11.

[0082] In Figure 7, the vertical axis represents the ratio of the potential change amounts of the ejection pulse PD, and the horizontal axis represents the viscosity of the ink. The ratio of the third potential change amount V3 to the second potential change amount V2 (V3 / V2) is shown as a negative value, and the ratio of the first potential change amount V1 to the second potential change amount V2 (V1 / V2) is shown as a positive value.

[0083] As shown in Figure 7, under constant ink discharge rate, the absolute value of the ratio (V1 / V2) decreases as the ink viscosity increases. Also, under constant ink discharge rate, the absolute value of the ratio (V3 / V2) increases as the ink viscosity increases.

[0084] Conventionally, in a discharge pulse PD1-4 having a first expansion element EE1, an expansion maintenance element EM0, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE in that order as shown in Figure 11, the discharge volume was kept constant by correcting the ratio (V3 / V2) of the third potential change amount V3 to the second potential change amount V2. In the case of such a discharge pulse PD-1, at a target discharge volume α, it is possible to keep the discharge volume constant by correcting the ratio (V3 / V2) under conditions where the viscosity is 4 mPa or higher, and at a target discharge volume β smaller than the target discharge volume α, it is possible to keep the discharge volume constant by correcting the ratio (V3 / V2) under conditions where the viscosity is 6.7 mPa or higher. However, the target discharge volume β cannot be achieved by correcting the ratio (V3 / V2).

[0085] On the other hand, in the discharge pulses PD1-1 and PD1-2 shown in Figures 8 and 9, which have a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE, it is possible to maintain a constant discharge amount even at the target discharge amount γ by correcting the ratio (V1 / V2) of the first potential change amount V1 to the second potential change amount V2. Furthermore, by correcting the ratio (V1 / V2), it is possible to maintain a constant discharge amount even at target discharge amounts β and γ, down to a range with lower ink viscosity.

[0086] Therefore, in the discharge pulse PD1 having a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE as described above, it is possible to maintain a constant discharge amount over a wide range of viscosities by correcting the ratio (V1 / V2) according to the viscosity of the ink.

[0087] If the viscosity indicated by viscosity information DV is the first viscosity ve1, the ratio (V1 / V2) corresponding to the target discharge volume β is the first value va1. If the viscosity indicated by viscosity information DV is the second viscosity ve2, which is higher than the first viscosity ve1, the ratio (V1 / V2) corresponding to the target discharge volume β is the second value va2, which is smaller than the first value va1. If the viscosity indicated by viscosity information DV is the third viscosity ve3, which is higher than the second viscosity ve2, the ratio (V1 / V2) corresponding to the target discharge volume β is the third value va3, which is smaller than the second value va2.

[0088] Figure 7 illustrates the first viscosity ve1, second viscosity ve2, third viscosity ve3, first value va1, second value va2, and third value va3 for a target discharge rate β. In the example shown in Figure 7, the first viscosity ve1 is approximately 2.3 mPa·s, the second viscosity ve2 is approximately 4.4 mPa·s, the third viscosity ve3 is approximately 6.7 mPa·s, the first value va1 is approximately 0.67, the second value va2 is approximately 0.25, and the third value va3 is approximately 0.

[0089] Thus, as the viscosity indicated by viscosity information DV increases, reducing the ratio of the first potential change amount V1 to the second potential change amount V2 (V1 / V2) reduces fluctuations in the discharge volume caused by the increase in liquid viscosity over a wider viscosity range of the liquid, and also suppresses unstable discharge. In other words, as the viscosity indicated by viscosity information DV decreases, increasing the ratio of the first potential change amount V1 to the second potential change amount V2 (V1 / V2) reduces fluctuations in the discharge volume caused by the increase in liquid viscosity over a wider viscosity range of the liquid, and also suppresses unstable discharge. Below, examples of correction of the discharge pulse PD1 will be explained based on Figures 8 to 11. In the following, examples mainly show the adjustment of the ratio (V1 / V2) and the ratio (V3 / V2), but the method is not limited to this, and other parameters such as discharge volume and discharge speed may be adjusted in conjunction with the adjustment of the ratio (V1 / V2) and the ratio (V3 / V2).

[0090] Figure 8 is an explanatory diagram of discharge pulse PD1-1, which is the discharge pulse PD1 when the viscosity indicated by viscosity information DV is the first viscosity ve1. As explained above based on Figure 5, discharge pulse PD1-1 has a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE.

[0091] Here, by making the sum of the duration of the first contraction element ES1 and the duration of the first contraction maintenance element ER1, that is, the period t1 from the start of the first contraction element ES1 to the start of the second contraction element ES2, approximately equal to half of the natural vibration period (Tc) of the discharge section 50, the vibration caused by the first contraction element ES1 can weaken the second contraction element ES2.

[0092] From this perspective, the period t1 from the start of the first contraction element ES1 to the start of the second contraction element ES2 is preferably 0.3 to 0.7 times the natural vibration period (Tc) of the discharge section 50, and more preferably 0.4 to 0.6 times the natural vibration period (Tc) of the discharge section 50. This allows the vibration of the first contraction element ES1 to suitably weaken the vibration of the second contraction element ES2. As a result, the correction range of the discharge amount based on the ratio of the first potential change amount V1 to the second potential change amount V2 can be increased.

[0093] Furthermore, by making the sum of the duration of the second contraction element ES2 and the duration of the second contraction maintenance element ER2, that is, the period t2 from the start of the second contraction element ES2 to the end of the second contraction maintenance element ER2, approximately equal to the natural vibration period (Tc) of the discharge section 50, the second contraction element ES2 can exert an effect of damping the residual vibration of the ink in the pressure chamber C after the ink has been discharged.

[0094] From this perspective, the period t2 from the starting end of the second contraction element ES2 to the end of the second contraction maintenance element ER2 is preferably 0.8 times or more and 1.2 times or less the natural vibration period (Tc) of the discharge section 50, and more preferably 0.9 times or more and 1.1 times or less the natural vibration period (Tc) of the discharge section 50. This suppresses the residual vibration of the ink in the pressure chamber C after the ink is discharged by the second contraction element ES2, thereby narrowing the ink discharge time interval and suppressing the deterioration of the subsequent ink discharge characteristics.

[0095] Figure 9 is an explanatory diagram of discharge pulse PD1-2, which is discharge pulse PD1 when the viscosity indicated by viscosity information DV is the second viscosity ve2. Discharge pulse PD1-2, like discharge pulse PD1-1 described above, has a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE.

[0096] However, the ratio (V1 / V2) in discharge pulse PD1-2 is smaller than the ratio (V1 / V2) in discharge pulse PD1-1 mentioned above. This makes it possible to bring the discharge amount when the viscosity indicated by viscosity information DV is the second viscosity ve2 closer to the discharge amount when the viscosity indicated by viscosity information DV is the first viscosity ve1.

[0097] In the example shown in Figure 9, the first potential change V1 in the discharge pulse PD1-2 is smaller than the first potential change V1 in the discharge pulse PD1-1. Here, it is preferable that the second potential change V2 when the viscosity indicated by viscosity information DV is the first viscosity ve1 and the second potential change V2 when the viscosity indicated by viscosity information DV is the second viscosity ve2 are equal to each other. This makes it possible to suitably reduce fluctuations in the discharge volume caused by an increase in the viscosity of the liquid.

[0098] Furthermore, the second potential change V2 in discharge pulse PD1-2 may be larger than the second potential change V2 in discharge pulse PD1-1, provided that the first potential change V1 in discharge pulse PD1-2 is smaller than the first potential change V1 in discharge pulse PD1-1. In other words, the ratio (V1 / V2) may be changed so that the sum of the first potential change V1 and the second potential change V2 does not change.

[0099] Figure 10 is an explanatory diagram of discharge pulse PD1-3, which is discharge pulse PD1 when the viscosity indicated by viscosity information DV is the third viscosity ve3. Discharge pulse PD1-3 does not have a first contraction element ES1 and a first contraction maintenance element ER1, but has a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE. By not having the first contraction element ES1 and the first contraction maintenance element ER1, the vibration caused by the second contraction maintenance element ER2 is not weakened. The ratio (V1 / V2) of discharge pulse PD1-3, which does not have the first contraction element ES1 and the first contraction maintenance element ER1, is 0, and the ratio (V1 / V2) in discharge pulse PD1-3 is smaller than the ratio (V1 / V2) in the aforementioned discharge pulse PD1-2.

[0100] Figure 11 is an explanatory diagram of discharge pulse PD1-4, which is another example of discharge pulse PD1 when the viscosity indicated by viscosity information DV is higher than the third viscosity ve3. Discharge pulse PD1-4, like discharge pulse PD1-3, does not have a first contraction element ES1 and a first contraction maintenance element ER1. However, discharge pulse PD1-4 has a first expansion element EE1 and an expansion maintenance element EM0. That is, discharge pulse PD1-4 does not have a first contraction element ES1 and a first contraction maintenance element ER1, but has a first expansion element EE1, an expansion maintenance element EM0, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE.

[0101] The first expansion element EE1 undergoes a potential change of a third potential change amount V3 so as to expand the pressure chamber C before the second contraction element ES2. The expansion maintenance element EM0 maintains the terminal potential of the first expansion element EE1 from the end of the first expansion element EE1 to the beginning of the second contraction element ES2. By using the first expansion element EE1 and the expansion maintenance element EM0 in this way, a shortage in the discharge volume can be suppressed even when the viscosity of the liquid is higher. Therefore, the discharge pulse PD1-4 may be used when the viscosity indicated by viscosity information DV is a fourth viscosity higher than the third viscosity ve3. In this case, as the viscosity indicated by viscosity information DV increases, adjustments may be made to increase the ratio of the third potential change amount V3 to the second potential change amount V2 (V3 / V2).

[0102] Here, by making the sum of the period of the first expansion element EE1 and the period of the expansion maintenance element EM0, that is, the period t3 from the start of the first expansion element EE1 to the start of the second contraction element ES2, approximately equal to half of the natural vibration period (Tc) of the discharge section 50, the timing of the reversal of vibration and the contraction overlap, which has the advantage of making it easier to secure the discharge volume and discharge speed.

[0103] From this perspective, the period t3 from the start of the first expansion element EE1 to the start of the second contraction element ES2 is preferably 0.3 times or more and 0.7 times or less the natural vibration period (Tc) of the discharge section 50, and more preferably 0.4 times or more and 0.6 times or less the natural vibration period (Tc) of the discharge section 50. This makes it possible to efficiently suppress insufficient discharge volume even when the viscosity of the liquid is higher.

[0104] As described above, in this embodiment, as the viscosity indicated by viscosity information DV increases, the ratio of the first potential change amount V1 to the second potential change amount V2 (V1 / V2) is reduced, thereby reducing fluctuations in the discharge amount caused by the increase in the viscosity of the liquid and suppressing unstable discharge over a wider viscosity change range of the liquid.

[0105] B: Second Embodiment The following describes a second embodiment of this disclosure. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0106] This embodiment is the same as the first embodiment, except that the waveform of the discharge pulse is different.

[0107] Figure 12 is an explanatory diagram of the discharge pulse PD3-1 in the second embodiment when the viscosity indicated by viscosity information DV is the first viscosity ve1. Discharge pulse PD3-1 is the same as discharge pulse PD1-1 in the first embodiment, except that a first expansion element EE1 and a first expansion maintenance element EM1 are added. That is, discharge pulse PD3-1 has the first expansion element EE1, the first expansion maintenance element EM1, the first contraction element ES1, the first contraction maintenance element ER1, the second contraction element ES2, the second contraction maintenance element ER2, and the expansion element EE in this order.

[0108] The first expansion element EE1 undergoes a potential change by a third potential change amount V3 so as to expand the pressure chamber C before the first contraction element ES1. The first expansion maintenance element EM1 maintains the terminal potential of the first expansion element EE1 from its end to the beginning of the first contraction element ES1. By using such a first expansion element EE1 and first expansion maintenance element EM1, the meniscus of the liquid inside the nozzle N can be stabilized by slightly drawing the meniscus into the nozzle N just before discharge, thereby reducing variations in discharge volume or discharge speed.

[0109] Here, the third potential change V3 is not particularly limited, but for example, it is about 0.2 × (V1 + V2).

[0110] Furthermore, by adding the first contraction element ES1 at a timing that resonates with the vibrations generated by the first expansion element EE1, and then adding the second contraction element ES2 at a timing that does not resonate with the vibrations of the first contraction element ES1, i.e., at a timing of half the natural vibration period (Tc) of the dispensing unit 50, the vibrations of the first contraction element ES1 suitably weaken the vibrations of the second contraction element ES2, thereby enabling stable dispensing of the desired amount even with low ink viscosity.

[0111] From this perspective, the period t4 from the start of the first expansion element EE1 to the start of the first contraction element ES1 is preferably 0.3 times or more and 0.7 times or less the natural vibration period (Tc) of the discharge section 50, and more preferably 0.4 times or more and 0.6 times or less the natural vibration period (Tc) of the discharge section 50. This allows for efficient discharge of liquid.

[0112] Figure 13 is an explanatory diagram of the discharge pulse PD3-2 in the second embodiment when the viscosity indicated by viscosity information DV is the second viscosity ve2. Similar to the discharge pulse PD3-1 described above, the discharge pulse PD3-2 has a first expansion element EE1, a first expansion maintenance element EM1, a first contraction element ES1, a first contraction maintenance element ER1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE in this order.

[0113] However, the ratio (V1 / V2) in discharge pulse PD3-2 is smaller than the ratio (V1 / V2) in discharge pulse PD3-1 mentioned above. This makes it possible to bring the discharge amount when the viscosity indicated by viscosity information DV is a second viscosity ve2 which is higher than the first viscosity ve1 closer to the discharge amount when the viscosity indicated by viscosity information DV is a first viscosity ve1.

[0114] In the example shown in Figure 13, the first potential change V1 in discharge pulse PD3-2 is smaller than the first potential change V1 in discharge pulse PD3-1. Here, because the first potential change V1 in discharge pulse PD3-2 is smaller than the first potential change V1 in discharge pulse PD3-1, the second potential change V2 in discharge pulse PD3-2 is larger than the second potential change V2 in discharge pulse PD3-1. In other words, the ratio (V1 / V2) is changed so that the sum of the first potential change V1 and the second potential change V2 does not change.

[0115] Furthermore, the second potential change V2 when the viscosity indicated by viscosity information DV is the first viscosity ve1 and the second potential change V2 when the viscosity indicated by viscosity information DV is the second viscosity ve2 may be equal to each other. In this case, fluctuations in the discharge volume caused by an increase in the viscosity of the liquid can be suitably reduced.

[0116] Figure 14 is an explanatory diagram of the discharge pulse PD3-3 in the second embodiment when the viscosity indicated by viscosity information DV is the third viscosity ve3. The discharge pulse PD3-3 does not have a first contraction element ES1 and a first contraction maintenance element ER1, but has a first expansion element EE1, a first expansion maintenance element EM1, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE.

[0117] Figure 15 is an explanatory diagram of another example of the discharge pulse PD3-4 in the second embodiment, where the viscosity indicated by viscosity information DV is the third viscosity ve3. Discharge pulse PD3-4, like discharge pulse PD3-3, does not have a first contraction element ES1 and a first contraction maintenance element ER1. However, discharge pulse PD3-4 has a second expansion element EE2 and a second expansion maintenance element EM2. That is, discharge pulse PD3-4 does not have a first contraction element ES1 and a first contraction maintenance element ER1, but has a first expansion element EE1, an expansion maintenance element EM0, a second expansion element EE2, a second expansion maintenance element EM2, a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE.

[0118] The second expansion element EE2 undergoes a potential change of a fourth potential change amount V4 so as to expand the pressure chamber C before the first expansion element EE1. The second expansion maintenance element EM2 maintains the terminal potential of the second expansion element EE2 from its end to the beginning of the first expansion element EE1. By using such a second expansion element EE2 and second expansion maintenance element EM2, a shortage in discharge volume can be suppressed even when the viscosity of the liquid is higher. Therefore, discharge pulses PD3-4 may be used when the viscosity indicated by viscosity information DV is a fourth viscosity higher than the third viscosity ve3. In this case, as the viscosity indicated by viscosity information DV increases, adjustments may be made to increase the ratio of the fourth potential change amount V4 to the second potential change amount V2 (V4 / V2).

[0119] Here, from the viewpoint of efficient discharge, it is preferable that the start timing of the first expansion element EE1 is the timing at which it resonates with the vibration generated in the second expansion element EE2, that is, approximately a period equal to the natural vibration period (Tc) of the discharge section 50 from the start of the second expansion element EE2. In other words, the period t5 from the start of the second expansion element EE2 to the start of the first expansion element EE1 is preferably 0.8 times or more and 1.2 times or less the natural vibration period (Tc) of the discharge section 50, and more preferably 0.9 times or more and 1.1 times or less the natural vibration period (Tc) of the discharge section 50.

[0120] Furthermore, the start timing of the second contraction element ES2 is preferably the timing at which it resonates with the vibration caused by the first expansion element EE1, that is, approximately half the natural vibration period (Tc) of the discharge section 50 from the start of the first expansion element EE1. In other words, the period t6 from the start of the first expansion element EE1 to the start of the second contraction element ES2 is preferably 0.3 to 0.7 times the natural vibration period (Tc) of the discharge section 50, and more preferably 0.4 to 0.6 times the natural vibration period (Tc) of the discharge section 50.

[0121] The second embodiment described above also reduces fluctuations in the discharge volume caused by an increase in the viscosity of the liquid over a wider range of viscosity changes, and suppresses unstable discharge.

[0122] C: Variant Each of the forms exemplified above can be modified in various ways. Specific examples of modifications that can be applied to each of the aforementioned forms are given below. Any form selected from the following examples can be combined as appropriate, provided they do not contradict each other.

[0123] C1: Variation 1 In the above-described embodiment, an example is given in which viscosity information DV is obtained based on vibration information NVT, temperature information DT, and input information DY. However, the embodiment is not limited to this, and for example, viscosity information DV may be obtained based on at least one of vibration information NVT, temperature information DT, and input information DY.

[0124] C2: Modification 2 In the above-described embodiment, an example is given in which residual vibration is detected using the inspection pulse PD2. However, the embodiment is not limited to this, and residual vibration may be detected using the discharge pulse PD1 as the inspection pulse. In other words, the discharge pulse PD1 may also serve as the "inspection pulse".

[0125] C3: Modification 3 In the above-described embodiment, an example is provided in which the discharge pulse PD1 and the inspection pulse PD2 are transmitted on a single signal line. However, the embodiment is not limited to this, and the discharge pulse PD1 and the inspection pulse PD2 may be transmitted on separate transmission lines. Furthermore, the drive signal Com may include signals or pulses other than the discharge pulse PD1 and the inspection pulse PD2.

[0126] C4: Modification 4 In the embodiments described above, a serial-type liquid dispensing device 100 was exemplified, in which a transporter 141 equipped with a head 151 is reciprocated. However, this disclosure also applies to a line-type liquid dispensing device in which multiple nozzles N are distributed across the entire width of the medium M.

[0127] C5: Modification 5 The liquid dispensing device 100 exemplified in the above-described form may be used in various devices such as facsimile machines and photocopiers, in addition to equipment dedicated to printing, and the applications of this disclosure are not particularly limited. However, the applications of the liquid dispensing device are not limited to printing. For example, a liquid dispensing device that dispenses a colorant solution can be used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. A liquid dispensing device that ejects a conductive material solution can be used as a manufacturing device for forming wiring and electrodes on a wiring board. A liquid dispensing device that ejects a solution of organic matter related to living organisms can be used, for example, as a manufacturing device for producing biochips.

[0128] D: Addendum A summary of this disclosure is provided below.

[0129] (Note 1) A first embodiment of a preferred example of a liquid dispensing device of the present disclosure comprises: a dispensing unit having a nozzle for dispensing liquid, a pressure chamber communicating with the nozzle, and a piezoelectric element driven to cause pressure fluctuations in the liquid in the pressure chamber in response to a supplied drive signal; a drive signal generation circuit for generating the drive signal; an acquisition unit for acquiring viscosity information indicating the viscosity of the liquid; and a control unit for controlling the operation of the drive signal generation circuit, wherein the drive signal includes a dispensing pulse for dispensing droplets from the nozzle, and the dispensing pulse includes a first contraction which changes the potential by a first potential change amount to contract the pressure chamber. The element comprises: an element; a first contraction maintenance element connected to the end of the first contraction element and maintaining the terminal potential of the first contraction element; and a second contraction element connected to the end of the first contraction maintenance element and changing its potential by a second potential change amount to contract the pressure chamber, wherein when the viscosity indicated by the viscosity information is a first viscosity, the ratio of the first potential change amount to the second potential change amount is a first value; and when the viscosity indicated by the viscosity information is a second viscosity higher than the first viscosity, the ratio of the first potential change amount to the second potential change amount is a second value smaller than the first value.

[0130] In the above embodiment, as the viscosity indicated by the viscosity information increases, the ratio of the first potential change to the second potential change is reduced, thereby reducing fluctuations in the discharge volume caused by the increase in the viscosity of the liquid and suppressing unstable discharge over a wider viscosity change range of the liquid.

[0131] (Note 2) In the second embodiment, which is a preferred example of the first embodiment, if the viscosity indicated by the viscosity information is a third viscosity that is higher than the second viscosity, the discharge pulse has the second contraction element but does not have the first contraction element and the first contraction maintenance element. In the above embodiment, if the viscosity of the liquid becomes too high, unstable discharge can be suitably suppressed by reducing unnecessary micro-vibrations.

[0132] (Note 3) In a third embodiment, which is a preferred example of the second embodiment, when the viscosity indicated by the viscosity information is the third viscosity, the discharge pulse includes a first expansion element that changes its potential by a third potential change amount so as to expand the pressure chamber before the second contraction element, and an expansion maintenance element that maintains the terminal potential of the first expansion element from the end of the first expansion element to the beginning of the second contraction element. In the above embodiment, even when the viscosity of the liquid is higher, a shortage of discharge volume can be suppressed.

[0133] (Note 4) In the fourth embodiment, which is a preferred example of the third embodiment, the period from the start of the first expansion element to the start of the first contraction element is 0.3 times or more and 0.7 times or less of the natural vibration period of the discharge section. In the above embodiment, even when the viscosity of the liquid is higher, the insufficient discharge volume can be efficiently suppressed.

[0134] (Note 5) In a fifth embodiment, which is a preferred example of the first embodiment, the discharge pulse includes a first expansion element whose potential changes by a third potential change amount so as to expand the pressure chamber before the first contraction element, and a first expansion maintenance element which maintains the terminal potential of the first expansion element from the end of the first expansion element to the beginning of the first contraction element. In the above embodiment, the meniscus of the liquid in the nozzle immediately before discharge can be stabilized, and as a result, variations in the discharge volume or discharge speed can be reduced.

[0135] (Note 6) In the sixth embodiment, which is a preferred example of the fifth embodiment, the period from the start of the first expansion element to the start of the first contraction element is 0.3 times or more and 0.7 times or less the natural vibration period of the discharge section. In the above embodiment, the liquid can be discharged efficiently.

[0136] (Note 7) In the seventh embodiment, which is a preferred example of the fifth embodiment, if the viscosity indicated by the viscosity information is a third viscosity that is higher than the second viscosity, the discharge pulse has a second contraction element but does not have the first contraction element and the first contraction maintenance element. In the above embodiments, when the viscosity of the liquid becomes too high, unstable discharge can be suitably suppressed by reducing unnecessary micro-vibrations.

[0137] (Note 8) In the eighth embodiment, which is a preferred example of the fifth embodiment, when the viscosity indicated by the viscosity information is a third viscosity higher than the second viscosity, the discharge pulse includes a second expansion element that changes potential to expand the pressure chamber before the first expansion element, and a second expansion maintenance element that maintains the terminal potential of the second expansion element from the end of the second expansion element to the beginning of the first expansion element. In the above embodiment, even when the viscosity of the liquid is higher, a shortage of discharge volume can be suppressed.

[0138] (Note 9) In the ninth embodiment, which is a preferred example of any of the first to eighth embodiments, the second potential change when the viscosity indicated by the viscosity information is the first viscosity and the second potential change when the viscosity indicated by the viscosity information is the second viscosity are equal to each other. In the above embodiments, fluctuations in the discharge volume caused by an increase in the viscosity of the liquid can be suitably reduced.

[0139] (Note 10) In the tenth embodiment, which is a preferred example of any of the first to ninth embodiments, the period from the start of the first contraction element to the start of the second contraction element is 0.3 times or more and 0.7 times or less the natural vibration period of the discharge section. In the above embodiment, the vibration caused by the first contraction element can be suitably weakened by the second contraction element. As a result, the correction range of the discharge amount based on the ratio of the first potential change amount to the second potential change amount can be increased.

[0140] (Note 11) In the 11th embodiment, which is a preferred example of any of the first to tenth embodiments, a detection circuit is further provided that acquires an electrical signal indicating the residual vibration of the liquid in the pressure chamber after the piezoelectric element has applied a pressure fluctuation to the liquid in the pressure chamber, and the acquisition unit acquires the viscosity information based on the electrical signal. In the above embodiments, viscosity information can be acquired without adding elements such as a temperature sensor.

[0141] (Note 12) In the twelfth embodiment, which is a preferred example of any of the first to tenth embodiments, a temperature sensor for detecting temperature is further provided, and the acquisition unit acquires the viscosity information based on the temperature detected by the temperature sensor. In the above embodiments, viscosity information indicating the change in viscosity due to a change in the temperature of the liquid can be directly acquired.

[0142] (Note 13) In the 13th embodiment, which is a preferred example of any of the 1st to 10th embodiments, a receiving unit for receiving input from a user is further provided, and the acquisition unit acquires the viscosity information based on the reception result from the receiving unit. In the above embodiments, viscosity information can be acquired according to the user's wishes. [Explanation of Symbols]

[0143] 50...Discharge section, 51...Flow path substrate, 52...Pressure chamber substrate, 53...Nozzle plate, 54...Vibration absorber, 55...Vibrating plate, 56...Piezoelectric element, 56_1~56_M...Piezoelectric element, 57...Protective substrate, 58...Case, 59...Wiring board, 100...Liquid dispensing device, 110...Liquid container, 120...Control module, 121...Control circuit, 121a...Acquisition section, 121b...Control section, 121c...Reception section, 122...Memory circuit, 123...Power supply circuit, 124...Drive signal generation circuit, 130...Transport mechanism, 140...Movement mechanism, 141...Transport body, 142...Transport belt, 150...Head module, 151...Head, 1 52...Drive circuit, 152a...Connection status specification circuit, 153...Detection circuit, 160...Temperature sensor, 170...Input device, 200...External device, C...Pressure chamber, Com...Drive signal, DT...Temperature information, DV...Viscosity information, DY...Input information, EE...Expansion element, EE1...First expansion element, EE2...Second expansion element, EM0...Expansion maintenance element, EM1...First expansion maintenance element, EM2...Second expansion maintenance element, ER1...First contraction maintenance element, ER2...Second contraction maintenance element, ES1...First contraction element, ES2...Second contraction element, Ea...Expansion element, Eb...Expansion maintenance element, Ec...Contraction element, F N...Nozzle surface, IO...Inlet, Img...Print data, L1...First row, L2...Second row, LHa...Wiring, LHd...Wiring, LHs...Wiring, M...Media, N...Nozzle, NVT...Vibration information, Na...Communication channel, PD1...Ejection pulse, PD1-1...Ejection pulse, PD1-2...Ejection pulse, PD1-3...Ejection pulse, PD1-4...Ejection pulse, PD2...Inspection pulse, PD3-1...Ejection pulse, PD3-2...Ejection pulse, PD3-3...Ejection pulse, PD3-4...Ejection pulse, R...Reservoir, R1...Space, R2...Space, Ra...Supply channel, S...Space, S1...Step, S2...Ste S3...step, S4...step, S5...step, SI...control signal, SLa...connection status specification signal, SLs...connection status specification signal, SWa...switch, SWs...switch, Sk1...control signal, Sk2...control signal, Tu...unit period, Tu1...period, Tu2...period, V0...reference potential, V1...first potential change, V2...second potential change, V3...third potential change, V4...fourth potential change, VBS...offset potential, VE...potential change, VHV...power supply potential, Vin...supply drive signal, Vout...output signal, dCom...waveform specification signal, t1...period, t2...period,t3…Period, t4…Period, t5…Period, t6…Period, va1…First value, va2…Second value, va3…Third value, ve1…First viscosity, ve2…Second viscosity, ve3…Third viscosity, α…Target discharge rate, β…Target discharge rate, γ…Target discharge rate.

Claims

1. A discharge unit having a nozzle for discharging liquid, a pressure chamber communicating with the nozzle, and a piezoelectric element that drives to cause pressure fluctuations in the liquid within the pressure chamber in response to a supplied drive signal, A drive signal generation circuit that generates the aforementioned drive signal, An acquisition unit that acquires viscosity information indicating the viscosity of a liquid, A control unit that controls the operation of the drive signal generation circuit, Equipped with, The drive signal includes a discharge pulse that causes a droplet to be ejected from the nozzle. The discharge pulse is A first contraction element that changes its potential by a first potential change amount so as to contract the pressure chamber, A first contraction maintenance element connected to the end of the first contraction element and maintaining the terminal potential of the first contraction element, A second contraction element is connected to the end of the first contraction maintenance element and changes its potential by a second potential change amount to contract the pressure chamber, It has, When the viscosity indicated by the viscosity information is the first viscosity, the ratio of the first potential change to the second potential change is the first value. If the viscosity indicated by the viscosity information is a second viscosity that is higher than the first viscosity, then the ratio of the first potential change amount to the second potential change amount is a second value that is smaller than the first value. A liquid dispensing device characterized by the following features.

2. If the viscosity indicated by the viscosity information is a third viscosity that is higher than the second viscosity, the discharge pulse has the second contraction element but does not have the first contraction element and the first contraction maintenance element. The liquid dispensing device according to feature 1.

3. If the viscosity indicated by the viscosity information is the third viscosity, The discharge pulse is A first expansion element whose potential changes by a third potential change amount so as to expand the pressure chamber before the second contraction element, An expansion maintenance element that maintains the terminal potential of the first expansion element from the end of the first expansion element to the beginning of the second contraction element, Having, The liquid dispensing device according to feature 2.

4. The period from the start of the first expansion element to the start of the first contraction element is 0.3 times or more and 0.7 times or less the natural vibration period of the discharge section. The liquid dispensing device according to feature 3.

5. The discharge pulse is A first expansion element whose potential changes by a third potential change amount so as to expand the pressure chamber before the first contraction element, A first expansion maintenance element that maintains the terminal potential of the first expansion element from the end of the first expansion element to the beginning of the first contraction element, Having, The liquid dispensing device according to feature 1.

6. The period from the start of the first expansion element to the start of the first contraction element is 0.3 times or more and 0.7 times or less the natural vibration period of the discharge section. The liquid dispensing device according to feature 5.

7. The discharge pulse is If the viscosity indicated by the viscosity information is a third viscosity that is higher than the second viscosity, the discharge pulse has the second contraction element but does not have the first contraction element and the first contraction maintenance element. The liquid dispensing device according to feature 5.

8. If the viscosity indicated by the viscosity information is a third viscosity that is higher than the second viscosity, The discharge pulse is A second expansion element that changes its potential to expand the pressure chamber before the first expansion element, A second expansion maintenance element that maintains the terminal potential of the second expansion element from the end of the second expansion element to the beginning of the first expansion element, Having, The liquid dispensing device according to feature 5.

9. The second potential change when the viscosity indicated by the viscosity information is the first viscosity and the second potential change when the viscosity indicated by the viscosity information is the second viscosity are equal to each other. The liquid dispensing device according to feature 1.

10. The period from the start of the first contraction element to the start of the second contraction element is 0.3 times or more and 0.7 times or less the natural vibration period of the discharge section. The liquid dispensing device according to feature 1.

11. The piezoelectric element further comprises a detection circuit that acquires an electrical signal indicating the residual vibration of the liquid in the pressure chamber after the piezoelectric element has applied pressure fluctuations to the liquid in the pressure chamber. The acquisition unit acquires the viscosity information based on the electrical signal. The liquid dispensing device according to feature 1.

12. It also includes a temperature sensor to detect temperature, The acquisition unit acquires viscosity information based on the temperature detected by the temperature sensor. The liquid dispensing device according to feature 1.

13. Furthermore, it includes a reception area for receiving user input, The acquisition unit acquires the viscosity information based on the reception result of the reception unit. The liquid dispensing device according to feature 1.

Images