Liquid ejection device

Abstract

This invention relates to a liquid ejection device. In the liquid ejection device, the driving signal includes an ejection pulse that ejects droplets from a nozzle. The ejection pulse has: a first contraction element that undergoes a potential change with a first potential change to contract a pressure chamber; a first contraction maintenance element connected to the terminal of the first contraction element and maintaining the terminal potential of the first contraction element; and a second contraction element connected to the terminal of the first contraction maintenance element and undergoing a potential change with a second potential change to contract the pressure chamber. When the viscosity shown in the viscosity information is a first viscosity, the ratio of the first potential change to the second potential change is a first value; when the viscosity shown in the viscosity information is a second viscosity higher than the first viscosity, the ratio of the first potential change to the second potential change is a second value less than the first value.

Description

Technical Field

[0001] This disclosure relates to a liquid ejection device. Background Technology

[0002] In liquid ejection devices, such as piezoelectric inkjet printers, a pressure change in the liquid within a pressure chamber is caused by supplying a drive signal to a piezoelectric element, thereby ejecting the liquid from a nozzle connected to the pressure chamber. In such liquid ejection devices, to suppress the decrease in ejection characteristics caused by changes in liquid viscosity, the drive signal is sometimes adjusted based on the liquid's viscosity. For example, Patent Document 1 discloses a liquid ejection device in which, to suppress the decrease in ejection characteristics caused by viscosity changes associated with liquid temperature variations, the potential change of the drive signal is adjusted based on the detection results of a temperature sensor that detects the liquid's temperature.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-20408

[0004] In the technology described in Patent Document 1, since only the potential change of the drive signal is adjusted, it is sometimes difficult to maintain the ejection characteristics as constant if the viscosity change of the liquid increases to above a predetermined value. Summary of the Invention

[0005] To solve the above technical problems, the preferred embodiment of the liquid ejection device disclosed herein includes: an ejection section having a nozzle, a pressure chamber, and a piezoelectric element, wherein the nozzle ejects liquid, the pressure chamber is connected to the nozzle, and the piezoelectric element is driven according to a supplied drive signal to cause pressure fluctuations in the liquid within the pressure chamber; a drive signal generation circuit for generating the drive signal; an acquisition section for acquiring viscosity information, the viscosity information representing the viscosity of the liquid; and a control section for controlling the operation of the drive signal generation circuit, the drive signal including an ejection pulse that causes droplets to be ejected from the nozzle, the ejection pulse having: a first contraction element with a first potential. The pressure chamber is contracted by a potential change in the amount of change; a first contraction maintaining element is connected to the terminal of the first contraction element and maintains the terminal potential of the first contraction element; and a second contraction element is connected to the terminal of the first contraction maintaining element and contracts the pressure chamber by a potential change in the amount of the second potential change. When the viscosity shown in the viscosity information is a first viscosity, the ratio of the first potential change to the second potential change is a first value. When the viscosity shown in the viscosity information is a second viscosity higher than the first viscosity, the ratio of the first potential change to the second potential change is a second value less than the first value. Attached Figure Description

[0006] Figure 1 This is a schematic diagram showing a structural example of the liquid ejection device according to the first embodiment.

[0007] Figure 2 This is a block diagram showing the electrical structure of the liquid ejection device according to the first embodiment.

[0008] Figure 3 This is a cross-sectional view of the head.

[0009] Figure 4 This is a diagram showing an example of the structure of a drive circuit.

[0010] Figure 5 This is an explanatory diagram of the ejection pulse and the check pulse included in the drive signal.

[0011] Figure 6 This is a flowchart illustrating a method for driving a liquid ejection device according to the first embodiment.

[0012] Figure 7 This is a graph showing the relationship between the viscosity of the liquid and the ratio of the potential change of the ejected pulse PD.

[0013] Figure 8 This is an explanatory diagram of the ejection pulse when the viscosity information shows the first viscosity.

[0014] Figure 9 This is an explanatory diagram of the ejection pulse when the viscosity shown in the viscosity information is the second viscosity.

[0015] Figure 10 This is an explanatory diagram of the ejection pulse when the viscosity information shows the third viscosity.

[0016] Figure 11 This is an illustration of another example of an ejection pulse when the viscosity shown in the viscosity information is the third viscosity.

[0017] Figure 12 This is an explanatory diagram of the ejection pulse when the viscosity shown in the viscosity information in the second embodiment is the first viscosity.

[0018] Figure 13 This is an explanatory diagram of the ejection pulse when the viscosity shown in the viscosity information in the second embodiment is the second viscosity.

[0019] Figure 14 This is an explanatory diagram of the ejection pulse when the viscosity information shown in the second embodiment is the third viscosity.

[0020] Figure 15 This is an explanatory diagram of another example of an ejection pulse when the viscosity information shown in the second embodiment is the third viscosity.

[0021] Explanation of reference numerals in the attached figures

[0022] 50…Ejection 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…Housing, 59…Wiring substrate, 100…Liquid ejection device, 110…Liquid container, 120…Control module, 121…Control circuit, 121a…Acquisition section, 121b…Control section, 121c…Receiving section, 122…Storage circuit, 123…Power supply circuit, 124…Drive signal generation circuit, 130…Conveying mechanism, 140…Moving mechanism, 141…Conveying body, 142…Conveyor belt, 150…Head module, 151…Head, 152…Drive circuit, 152a… Connection status specified 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, FN…nozzle face, IO…inlet, Img…printing data L1…First column, L2…Second column, LHa…Wiring, LHd…Wiring, LHs…Wiring, M…Medium, N…Nozzle, NVT…Vibration information, Na…Connecting flow path, PD1…Ejection pulse, PD1-1…Ejection pulse, PD1-2…Ejection pulse, PD1-3…Ejection pulse, PD1-4…Ejection pulse, PD2…Check 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 flow path, S…Space, S1…Step, S2…Step, 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 ejection rate, β…target ejection rate, γ…target ejection rate. Detailed Implementation

[0023] The preferred embodiments of this disclosure will now be described with reference to the accompanying drawings. It should be noted that the dimensions and scales of the parts in the drawings may differ slightly from actual dimensions, and some parts may be shown schematically for ease of understanding. Furthermore, unless otherwise specified in the following description, the scope of this disclosure is not limited to these embodiments.

[0024] To facilitate the determination of position or orientation, the following explanation will use intersecting X-axis, Y-axis, and Z-axis. Furthermore, the direction along the X-axis is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 and Y2 directions. Additionally, the opposite directions along the Z-axis are the Z1 and Z2 directions.

[0025] Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis may not be a vertical axis. In addition, the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, but are not limited to this; for example, they may intersect at an angle between 80° and 100°.

[0026] A: First Implementation Method

[0027] A1: Overall structure of the liquid ejection device

[0028] Figure 1 This is a schematic diagram showing a structural example of the liquid ejection device 100 according to the first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects an example of "liquid," namely ink, as droplets toward a medium M. For example, the medium M is printing paper. It should be noted that the medium M is not limited to printing paper; for example, it can be any printing material such as resin film or cloth.

[0029] like Figure 1 As shown, the liquid ejection device 100 includes: a liquid container 110, a control module 120, a conveying mechanism 130, a moving mechanism 140, a head module 150, a temperature sensor 160, and an input device 170.

[0030] Liquid container 110 stores ink. Specific examples of liquid container 110 include a housing that can be detachably attached to the liquid dispensing device 100, a bag-shaped ink pouch made of a flexible membrane, and an ink canister for refilling ink. It should be noted that the type of ink stored in liquid container 110 is arbitrary.

[0031] The control module 120 controls the operation of various elements of the liquid ejection device 100. Details regarding the control module 120 will follow. Figure 2 Please provide an explanation.

[0032] Under the control of the control module 120, the conveying mechanism 130 conveys the medium M along the Y-axis.

[0033] Under the control of the control module 120, the moving mechanism 140 causes the head module 150 to reciprocate along the X-axis. The moving mechanism 140 has a generally box-shaped conveyor body 141, referred to as a carriage, that houses the head module 150, and an annular conveyor belt 142 to which the conveyor body 141 is fixed. It should be noted that the number of head modules 150 mounted on the conveyor body 141 is not limited to one, and can be multiple. In addition, the aforementioned liquid container 110 can also be mounted on the conveyor body 141, besides the head module 150.

[0034] Under the control of the control module 120, the head module 150 ejects ink supplied from the liquid container 110 from each of the multiple nozzles onto the medium M. This ejection, in parallel with the transport of the medium M based on the transport mechanism 130 and the reciprocating movement of the head module 150 based on the moving mechanism 140, forms an ink-based image on the surface of the medium M.

[0035] Temperature sensor 160 detects temperature. More specifically, temperature sensor 160 is, for example, a resistive temperature sensor such as a linear resistor or a thermistor, detecting the temperature of the ink within the pressure chamber C, described later. Figure 1 In the example shown, temperature sensor 160 is located on head module 150. It should be noted that the location of temperature sensor 160 is not limited to... Figure 1 The example shown could be a location where the temperature of the ink in the pressure chamber C (described later) can be directly detected, or a location where a detection result can be obtained to estimate the temperature of the ink in the pressure chamber C (described later); there are no particular limitations. Furthermore, the temperature sensor 160 is not limited to a resistance temperature sensor; it could also be an optical temperature sensor.

[0036] Input device 170 is a device that receives input from a user and outputs input information DY based on the user's input. For example, input device 170 may include an operation panel or a remote control light receiver. For example, an operation panel may be disposed on the outer frame of the liquid dispensing device 100, and output the input information DY as an electrical signal, the input being based on the user's operation of the remote control. For example, a remote control light receiver may receive an infrared signal from a remote control, decode the infrared signal, and output the input information DY as an electrical signal, the input being based on the user's operation of the remote control. It should be noted that input device 170 is provided as needed and may be omitted.

[0037] A2: Electrical structure of the liquid ejection device

[0038] Figure 2 This is a block diagram showing the electrical structure of the liquid ejection device 100 according to the first embodiment. (As shown) Figure 2 As shown, the head module 150 includes a head 151, a drive circuit 152, and a detection circuit 153.

[0039] The head 151 has multiple ejection sections 50. Each ejection section 50 is a structure for ejecting ink, as will be discussed later based on... Figure 3 As described, it has a nozzle N, a pressure chamber C, and a piezoelectric element 56.

[0040] The 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 of 2 or more. It should be noted that, hereinafter, without distinguishing between piezoelectric elements 56_1 to 56_M, each of them is sometimes referred to as piezoelectric element 56. In addition, hereinafter, for the M other constituent elements in the liquid ejection device 100 corresponding to piezoelectric elements 56, the subscripts "_1 to_M" or "[1] to [M]" are sometimes used as reference numerals to show the correspondence with piezoelectric elements 56_1 to 56_M.

[0041] Each piezoelectric element 56 receives a drive signal Vin and is driven by the inverse piezoelectric effect. Additionally, each piezoelectric element 56 outputs an output signal Vout via the piezoelectric effect. It should be noted that the details of the first 151 will be discussed later based on... Figure 3 Please provide an explanation.

[0042] It should be noted that, in Figure 2 In the example shown, the number of headers 151 in the header module 150 is one, but it is not limited to this. The number of headers 151 in the header module 150 can also be two or more.

[0043] Under the control of the control module 120, the drive circuit 152 drives the piezoelectric element 56. Specifically, under the control of the control module 120, the drive circuit 152 switches whether to supply the drive signal Com output from the control module 120 as the supply drive signal Vin for each of the plurality of piezoelectric elements 56 on the head 151. Furthermore, in this embodiment, under the control of the control module 120, the drive circuit 152 also switches whether to supply the electromotive force in each of the plurality of piezoelectric elements 56 on the head 151 as the output signal Vout to the detection circuit 153. It should be noted that detailed information about the drive circuit 152 will be provided later based on... Figure 4 Please provide an explanation.

[0044] The detection circuit 153 detects the residual vibration generated in the pressure chamber C when the inspection pulse PD2 (described later) is supplied to the piezoelectric element 56. Here, the detection circuit 153 generates vibration information NVT representing the residual vibration based on the electrical signals Vout generated by each piezoelectric element 56. For example, the detection circuit 153 generates the vibration information NVT by amplifying the output signal Vout after removing noise. Residual vibration refers to the vibration remaining in the pressure chamber C after the piezoelectric element 56 is driven, vibrating at the natural vibration period (Tc) of the ejection section 50. As described above, the detection circuit 153 acquires the vibration information NVT as an electrical signal, which represents the residual vibration of the liquid in the pressure chamber C after the piezoelectric element 56 imparts a pressure change to the liquid in the pressure chamber C.

[0045] like Figure 2 As shown, the control module 120 includes: a control circuit 121, a storage circuit 122, a power supply circuit 123, and a drive signal generation circuit 124.

[0046] The control circuit 121 has the function of controlling the operation of each part of the liquid ejection device 100 and processing various data.

[0047] For example, the control circuit 121 may include one or more processors such as a CPU (Central Processing Unit). It should be noted that the control circuit 121 may replace the CPU or, in addition to the CPU, also incorporate a programmable logic device such as an FPGA (Field-Programmable Gate Array). Furthermore, when the control circuit 121 is composed of multiple processors, for example, different processors may be used to control the operation of the drive circuit 152 and the detection circuit 153. Additionally, when the control circuit 121 is composed of multiple processors, these multiple processors may be mounted on different substrates.

[0048] Storage circuit 122 stores various programs executed by control circuit 121, as well as various data such as printed data Img processed by control circuit 121. For example, storage circuit 122 includes one or both of the following 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 Read-Only Memory). Printed data Img is supplied from external device 200 such as personal computer or digital camera. It should be noted that storage circuit 122 may also be partially or entirely incorporated into control circuit 121.

[0049] The storage circuit 122 stores vibration information NVT, temperature information DT, input information DY, and viscosity information DV.

[0050] Vibration information NVT is information indicating residual vibration detected by detection circuit 153 when a check pulse PD2 (described later) is supplied to piezoelectric element 56.

[0051] Temperature information DT indicates the temperature detected by temperature sensor 160. The temperature shown in temperature information DT is the temperature of the ink in pressure chamber C, as described later, or a temperature corresponding to that temperature.

[0052] Input information DY represents the user's input to input device 170 as the processing result of processing unit 121c (described later). Input information DY is information related to the viscosity of the ink in ejection unit 50, such as ink viscosity characteristics information, ink type information, etc.

[0053] Viscosity information (DV) indicates the viscosity of the liquid. The viscosity shown in DV is the viscosity of the ink in pressure chamber C, which will be described later.

[0054] The power supply circuit 123 receives power from a commercial power supply not shown and generates various predetermined potentials. These potentials are appropriately supplied to various parts of the liquid ejection device 100. 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. Additionally, the power supply potential VHV is supplied to the drive signal generation circuit 124.

[0055] The drive signal generation circuit 124 is a circuit that generates drive signals Com for driving each piezoelectric element 56. Specifically, for example, the drive signal generation circuit 124 includes 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, the signal of the waveform actually supplied to the piezoelectric element 56 (the ejection pulse PD1 or check pulse PD2 described later) in the waveform included in the drive signal Com is the aforementioned supply drive signal Vin. The waveform specification signal dCom is a digital signal used to specify the waveform of the drive signal Com.

[0056] In the control module 120 described above, the control circuit 121 controls the operation of each part of the liquid ejection device 100 by executing the program stored in the storage circuit 122. Here, the control circuit 121 generates control signals Sk1 and Sk2, control signal SI, and waveform specification signal dCom as signals for controlling the operation of each part of the liquid ejection device 100 through the execution of the program.

[0057] Control signal Sk2 is used to control the drive of the conveyor mechanism 130. Control signal Sk1 is used to control the drive of the moving mechanism 140. Control signal SI is a digital signal used to specify the operating state of the piezoelectric element 56. It should be noted that the control signal SI may also include a timing signal for specifying the timing of the drive of the piezoelectric element 56. For example, this timing signal is generated based on the output of an encoder that detects the position of the aforementioned conveyor body 141.

[0058] Furthermore, the control circuit 121 functions as the acquisition unit 121a, control unit 121b, and receiving unit 121c by executing the program stored in the storage circuit 122. Thus, the liquid dispensing device 100 includes the acquisition unit 121a, control unit 121b, and receiving unit 121c.

[0059] 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 storage circuit 122.

[0060] To be more specific, the higher the viscosity of the ink in pressure chamber C (described later), the higher the attenuation rate of the residual vibration amplitude. Therefore, by pre-observing the relationship between the ink viscosity and the attenuation of the residual vibration amplitude, the acquisition unit 121a acquires viscosity information DV based on the attenuation state of the residual vibration amplitude shown in 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. Thus, viscosity information DV can be acquired even without adding components such as a temperature sensor 160. Alternatively, viscosity information DV can be acquired even when using ink with unknown properties.

[0061] Furthermore, the higher the temperature of the ink in pressure chamber C (described later), the lower the viscosity of the ink. Therefore, by pre-observing the relationship between the ink's viscosity and temperature, the acquisition unit 121a acquires viscosity information DV based on the temperature shown by temperature information DT and this relationship. In this way, the acquisition unit 121a acquires viscosity information DV based on the detected temperature of temperature sensor 160. Thus, viscosity information DV, which represents the viscosity change associated with temperature changes in the liquid, can be directly acquired. Here, the aforementioned relationship between the ink's viscosity and the attenuation rate of the residual vibration amplitude varies depending on the ink's temperature. Therefore, when acquiring viscosity information DV based on vibration information NVT, the acquisition unit 121a can acquire the correlation between viscosity information DV and temperature information DT based on viscosity information DV and temperature information DT. During continuous use of the same ink, viscosity information DV can be acquired from the detected temperature information DT by referring to the acquired correlation between viscosity information DV and temperature information DT.

[0062] 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 acceptance result of the acceptance unit 121c, i.e., the input information DY. Thus, it is possible to acquire viscosity information DV corresponding to the input information DY input by the user, which is related to the type of ink used. Here, the input information DY can also be viscosity information DV, and the acquisition unit 121a can directly acquire viscosity information DV based on the input information DY. Alternatively, the acquisition unit 121a can acquire viscosity information DV based on vibration information NVT, after acquiring or correcting the relationship between the ink viscosity and the inherent vibration period of residual vibration, based on the input information DY. Furthermore, the acquisition unit 121a can also acquire viscosity information DV based on temperature information DT, after acquiring or correcting the relationship between the ink viscosity and temperature, based on the information shown in the input information DY.

[0063] The control unit 121b controls the operation of the drive signal generation circuit 124. Here, the control unit 121b corrects the ejection pulse PD1 (described later) based on the viscosity information DV.

[0064] The receiving unit 121c receives input from the user. In this embodiment, the receiving unit 121c receives input information DY, which represents the input result of the input device 170 based on the user's operation.

[0065] A3: Head

[0066] Figure 3 This is a sectional view of the head 151. (Example) Figure 3 As shown, the head 151 has a plurality of nozzles N for ejecting ink. The plurality of nozzles N are divided into a first column L1 and a second column L2 arranged with gaps between them in the direction along the X-axis. The first column L1 and the second column L2 are each a collection of a plurality of nozzles N arranged in a straight line in the direction along the Y-axis.

[0067] Head 151 has a structure that is approximately symmetrical to each other along the X-axis. The positions of the plurality of nozzles N in the first column L1 and the plurality of nozzles N in the second column L2 along the Y-axis can be either the same or different. Figure 3 The example illustrates a structure in which the positions of multiple nozzles N in the first column L1 and multiple nozzles N in the second column L2 are aligned with each other along the Y-axis.

[0068] like Figure 3 As shown, the head 151 includes: a flow path substrate 51, a pressure chamber substrate 52, a nozzle plate 53, a vibration absorber 54, a vibrating plate 55, a plurality of piezoelectric elements 56, a protective substrate 57, a housing 58, and a wiring substrate 59.

[0069] The flow path substrate 51 and the pressure chamber substrate 52 are stacked in the Z1 direction in the order of flow path substrate 51 and pressure chamber substrate 52 to form a flow path for supplying ink to a plurality of nozzles N. In a region located further in the Z1 direction than the stack formed by the flow path substrate 51 and the pressure chamber substrate 52, a vibrating plate 55, a plurality of piezoelectric elements 56, a protective substrate 57, a housing 58, a wiring substrate 59, and a drive circuit 152 are provided. On the other hand, in a region located further in the Z2 direction than the stack, a nozzle plate 53 and a vibration absorber 54 are provided. Each element of the head 151 is schematically a strip-shaped plate in the Y direction, joined together, for example, by an adhesive. Hereinafter, each element of the head 151 will be described sequentially.

[0070] The nozzle plate 53 is a plate-shaped component having a plurality of nozzles N, each in a first row L1 and a second row L2. Each of the plurality of nozzles N has 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. For example, the nozzle plate 53 is manufactured by processing a silicon single-crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. Other known methods and materials may also be appropriately used in the manufacture of the nozzle plate 53. In addition, the cross-sectional shape of the nozzle is typically circular, but not limited to this; for example, it may be a non-circular shape such as a polygon or an oval.

[0071] On the flow path substrate 51, for each of the first column L1 and the second column L2, there is a space R1, a plurality of supply flow paths Ra, and a plurality of connecting flow paths Na. In a top view along the Z-axis, the space R1 is an elongated opening extending along the Y-axis. Each of the supply flow paths Ra and the connecting flow paths Na is a through-hole formed for each nozzle N. Each supply flow path Ra is connected to the space R1.

[0072] The pressure chamber substrate 52 is a plate-shaped component having multiple pressure chambers C, referred to as cavities, for each of the first column L1 and the second column L2. The multiple pressure chambers C are arranged in the direction along the Y-axis. Each pressure chamber C is formed according to each nozzle N and is an elongated space extending in the direction along the X-axis when viewed from above.

[0073] The flow path substrate 51 and the pressure chamber substrate 52 are manufactured in the same manner as the aforementioned nozzle plate 53, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. Other known methods and materials may be appropriately used in the manufacture of the flow path substrate 51 and the pressure chamber substrate 52.

[0074] Pressure chamber C is located between flow path substrate 51 and vibrating plate 55. For each of the first column L1 and the second column L2, multiple pressure chambers C are arranged along the Y-axis. Furthermore, pressure chamber C is connected to both the connecting flow path Na and the supply flow path Ra. Thus, pressure chamber C is connected to nozzle N via connecting flow path Na and to space R1 via supply flow path Ra.

[0075] A vibrating plate 55 is disposed on the Z1-oriented surface of the pressure chamber substrate 52. The vibrating plate 55 is a plate-shaped component capable of elastic vibration. For example, the vibrating plate 55 has an elastic film made of silicon oxide (SiO2) and an insulating film made of zirconium oxide (ZrO2), which are stacked in the Z1 direction in the order of elastic film and insulating film. For example, the elastic film is formed by thermal oxidation of one side of a silicon single crystal substrate. For example, the insulating film is formed by sputtering a zirconium layer and then thermally oxidizing the layer. It should be noted that the vibrating plate 55 is not limited to a structure based on the aforementioned stacked elastic film and insulating film; for example, it may be composed of a single layer or three or more layers.

[0076] On the Z1-oriented surface of the vibrating plate 55, for each of the first column L1 and the second column L2, a plurality of piezoelectric elements 56 corresponding to nozzles N are arranged. Each piezoelectric element 56 is driven according to a supplied drive signal Com, causing pressure fluctuations in the ink within the pressure chamber C. Each piezoelectric element 56, when viewed from above, appears as an elongated strip extending along the X-axis. The plurality of piezoelectric elements 56 are arranged along the Y-axis in a manner corresponding to the plurality of pressure chambers C. The piezoelectric elements 56 overlap with the pressure chambers C when viewed from above.

[0077] Although not illustrated, each piezoelectric element 56 has a first electrode, a piezoelectric layer, and a second electrode, and is stacked in the Z1 direction in the order of the first electrode, the piezoelectric layer, and the second electrode. One of the first and second electrodes is a separate electrode arranged separately for each piezoelectric element 56, and a drive signal Com is supplied to this electrode. The other electrode is a strip-shaped common electrode extending continuously along the Y-axis in a manner that covers multiple piezoelectric elements 56, and a constant offset potential VBS is supplied to this other electrode, for example. Examples of metal materials used for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), among which one can be used alone, or two or more can be used in combination, such as in alloys or in a stack. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3), and for example, is a strip-shaped material extending continuously along the Y-axis in a manner that covers multiple piezoelectric elements 56. Here, in the piezoelectric layer, in the region corresponding to the gap between adjacent pressure chambers C when viewed from above, a through hole extending through the piezoelectric layer extends in the direction along the X-axis. If the vibrating plate 55 vibrates in conjunction with the deformation of the piezoelectric element 56, the pressure in the pressure chamber C changes, thereby ejecting ink from the nozzle N. It should be noted that the piezoelectric layer can also be provided individually for each piezoelectric element 56.

[0078] The protective substrate 57 is a plate-shaped component disposed on the Z1-oriented surface of the vibrating plate 55, protecting the plurality of piezoelectric elements 56 and enhancing the mechanical strength of the vibrating plate 55. Here, the plurality of piezoelectric elements 56 are accommodated in the space S between the protective substrate 57 and the vibrating plate 55. For example, the protective substrate 57 is made of resin material.

[0079] Housing 58 is a housing for storing ink supplied to multiple pressure chambers C. For example, housing 58 is made of resin material. In housing 58, spaces R2 are provided for each of the first column L1 and the second column L2. Spaces R2 communicate with the aforementioned space R1 and, together with space R1, function as reservoirs R for storing ink supplied to the multiple pressure chambers C. Housing 58 is provided with inlets IO for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chamber C via respective supply flow paths Ra.

[0080] The vibration absorber 54, also known as a flexible substrate, is a flexible resin film that forms the wall of the reservoir R and absorbs pressure fluctuations of the ink within the reservoir R. It should be noted that the vibration absorber 54 can also be a flexible thin metal sheet. The Z1-facing surface of the vibration absorber 54 is bonded to the flow path substrate 51 using an adhesive or similar agent.

[0081] The wiring substrate 59 is mounted on the Z1-oriented surface of the vibrating plate 55 and serves as a mounting component for electrically connecting the control module 120 to the head 151. For example, the wiring substrate 59 is a flexible wiring substrate such as COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable). In this embodiment, the aforementioned drive circuit 152 is mounted on the wiring substrate 59. It should be noted that the wiring substrate 59 can also be a rigid substrate. In this case, the drive circuit 152 is mounted on the rigid substrate or on a flexible substrate connected to the rigid substrate.

[0082] A4: Details of the drive circuit

[0083] Figure 4 This is a diagram showing an example of the structure of the drive circuit 152. (As shown...) Figure 4 As shown, wirings LHd, LHa, and LHs are connected in the drive circuit 152. Wiring LHd is the power supply line supplied with the offset potential VBS. Wiring LHa is the signal line that transmits the drive signal Com. Wiring LHs is the signal line that transmits the output signal Vout.

[0084] The drive circuit 152 has: M switches SWa (SWa[1] to SWa[M]), M switches SWs (SWs[1] to SWs[M]), and a connection state specifying circuit 152a that specifies the connection state of these switches.

[0085] Switch SWa [m] is a switch that toggles the conduction (on) and non-conductivity (off) between wiring LHa, used for transmitting the drive signal Com, and piezoelectric element 56 [m]. Here, m is a natural number greater than 1 and less than M. Switch SWs [m] is a switch that toggles the conduction (on) and non-conductivity (off) between wiring LHs, used for transmitting the output signal Vout, and piezoelectric element 56 [m]. Each of these switches is, for example, a transmission gate.

[0086] The connection status specifying circuit 152a generates connection status specifying signals SLa[1] to SLa[M] for the on / off state of specified switches SWa[1] to SWa[M] and connection status specifying signals SLs[1] to SLs[M] for the on / off state of specified switches SWs[1] to SWs[M] based on the control signal SI.

[0087] The switching switch SWA[m] is turned on and off according to the connection state specification signal SLa[m] generated as described above. For example, the switch SWA[m] is in the on state when the connection state specification signal SLa[m] is high and in the off state when it is low. As described above, the drive circuit 152 supplies a portion or all of the waveform of the drive signal Com to one or more piezoelectric elements 56 selected from piezoelectric elements 56_1 to 56_M as the supply drive signal Vin.

[0088] Furthermore, the switch SWs[m] is switched on and off according to the connection state specification signal SLs[m]. For example, the switch SWs[m] is in the on state when the connection state specification signal SLs[m] is high, and in the off state when it is low. As described above, the drive circuit 152 supplies the output signal Vout of one or more piezoelectric elements 56 selected from piezoelectric elements 56_1 to 56_M to the detection circuit 153.

[0089] A5: Drive signal

[0090] Figure 5 This is an explanatory diagram of the ejection pulse PD1 and the check pulse PD2 included in the drive signal Com. (See diagram below.) Figure 5 As shown, the drive signal Com includes an ejection pulse PD1 and a check pulse PD2, which are repeated within a unit period Tu. The unit period Tu is divided into a preceding period Tu1, which includes the ejection pulse PD1, and a subsequent period Tu2, which includes the check pulse PD2. Figure 5 In the example shown, 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.

[0091] It should be noted that the switching of switches SWA[m] and SWs[m] can also be performed within a shorter control period than period Tu1 or period Tu2. Furthermore, the lengths of period Tu1 and period Tu2 can be different from each other. Additionally, although the diagram is omitted, the switching of switches SWA[2] to SWA[M] and switches SWs[2] to SWs[M] will also be performed using periods Tu1 and Tu2 respectively as control periods.

[0092] The ejection pulse PD1 is a pulse used to eject ink as droplets from nozzle N. The ejection pulse PD1 is supplied to the piezoelectric element 56, causing pressure fluctuations in the ink within pressure chamber C, thereby ejecting the ink from nozzle N. Figure 5 In the example shown, the ejected 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 sequence.

[0093] The first contraction element ES1 undergoes a potential change with a first potential change amount V1 to cause the pressure chamber C to contract. The first contraction maintenance element ER1 is connected to the terminal 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 terminal of the first contraction maintenance element ER1 and undergoes a potential change with a second potential change amount V2 to cause the pressure chamber C to contract. The second contraction maintenance element ER2 is connected to the terminal 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 cause the pressure chamber C to expand.

[0094] Here, the initial potential of the first contraction element ES1 and the terminal potential of the expansion element EE are respectively the reference potential V0.

[0095] The check pulse PD2 is used to detect residual vibration. The check pulse PD2 is supplied to the piezoelectric element 56, thereby causing pressure fluctuations in the ink within the pressure chamber C even when no ink is ejected from the nozzle N. Figure 5 In the example shown, the pulse PD2 has an expansion element Ea, an expansion maintenance element Eb, and a contraction element Ec in sequence.

[0096] The expansion element Ea changes its potential by a potential change VE to expand the pressure chamber C. The expansion maintenance element Eb is connected to the terminal 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 VE to contract the pressure chamber C. In this way, the potential of the check pulse PD2 drops to a level lower than the reference potential V0, is maintained at that level for a predetermined time, and then returns to the reference potential V0. It should be noted that the waveform of the check pulse PD2 is only required to cause pressure fluctuations in the ink within the pressure chamber C without ink being ejected from the nozzle N; it is not limited to... Figure 5 The examples shown are arbitrary.

[0097] A6: Driving method of liquid ejection device

[0098] Figure 6 This is a flowchart illustrating a driving method for the liquid ejection device 100 according to the first embodiment. The driving method is as follows... Figure 6 As shown, steps S1 to S5 are included in sequence. It should be noted that the order of steps S1 to S3 can be earlier than step S4, and is not limited to the example shown in the figure; it is arbitrary.

[0099] In step S1, the control circuit 121, which functions as the receiving unit 121c, receives the input information DY. More specifically, in step S1, the receiving 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 storage circuit 122.

[0100] Following step S1, in step S2, the control circuit 121 acquires the temperature information DT. More specifically, in step S2, the control circuit 121 acquires the detection result of the temperature sensor 160 as the temperature information DT. The acquired temperature information DT is stored in the storage circuit 122. It should be noted that, as mentioned above, step S2 can be performed before step S4, or it can be performed before step S1.

[0101] Following step S2, in step S3, control circuit 121 acquires vibration information NVT. More specifically, in step S3, control circuit 121 acquires vibration information NVT from detection circuit 153. Vibration information NVT represents the residual vibration of the ink in pressure chamber C after pressure variation caused by supplying a check pulse PD2 to piezoelectric element 56. The acquired vibration information NVT is stored in storage circuit 122. It should be noted that, as mentioned above, step S3 can be performed before step S4, or it can be performed before step S1 or step S2.

[0102] Following steps S1 to S3 above, in step S4, the control circuit 121, which functions as the acquisition unit 121a, acquires viscosity information DV based on input information DY, temperature information DT, and vibration information NVT. The acquired viscosity information DV is stored in the storage circuit 122.

[0103] Following step S4, in step S5, the control circuit 121, which functions as the control unit 121b, corrects the ejection pulse PD1 based on the viscosity information DV. This correction will be described in detail below.

[0104] A7: Correction of ejection pulse

[0105] Figure 7 This is a graph showing the relationship between the viscosity of the liquid and the ratio of the potential change of the ejection pulse (PD). Figure 7 The diagram illustrates the relationship between the ink viscosity and the ratio (V1 / V2) of the first potential change V1 to the second potential change V2, and the relationship between the ink viscosity and the ratio (V3 / V2) of the third potential change V3 to the second potential change V2, assuming the actual ejection volume is the target ejection volume α, β, γ. Here, the sum of the first potential change V1 and the second potential change V2 is constant. The third potential change V3 is... Figure 11 The potential change of the first expansion element EE1, which will be described later, is shown.

[0106] It should be noted that, in Figure 7 In the diagram, the vertical axis represents the ratio of the potential change of the ejected pulse PD, and the horizontal axis represents the viscosity of the ink. The ratio of the third potential change V3 to the second potential change V2 (V3 / V2) is shown as a negative value, while the ratio of the first potential change V1 to the second potential change V2 (V1 / V2) is shown as a positive value.

[0107] like Figure 7 As shown, with a constant ejection volume, the higher the ink viscosity, the smaller the absolute value of the ratio (V1 / V2). Conversely, with a constant ejection volume, the higher the ink viscosity, the larger the absolute value of the ratio (V3 / V2).

[0108] In the past, Figure 11In the ejection pulses PD1-4 shown, which sequentially include 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, the following processing is performed: the ejection quantity is kept constant by correcting the ratio (V3 / V2) of the third potential change V3 relative to the second potential change V2. In the case of such ejection pulses PD1-4, the target ejection quantity α can be kept constant by correcting the ratio (V3 / V2) when the viscosity is 4 mPa or higher. Similarly, the target ejection quantity β, which is less than the target ejection quantity α, can be kept constant by correcting the ratio (V3 / V2) when the viscosity is 6.7 mPa·s or higher. However, the target ejection quantity β cannot be achieved by correcting the ratio (V3 / V2).

[0109] On the other hand, Figure 8 as well as Figure 9 In the ejection pulses PD1-1 and PD1-2 shown, which have a first shrinkage element ES1, a first shrinkage maintenance element ER1, a second shrinkage element ES2, a second shrinkage maintenance element ER2, and an expansion element EE, the ejection volume can be kept constant even for the target ejection volume γ by correcting the ratio (V1 / V2) of the first potential change V1 to the second potential change V2. Furthermore, by correcting the ratio (V1 / V2), the ejection volume can be kept constant even for target ejection volumes β and γ, up to a range where the ink viscosity is lower.

[0110] Therefore, in the ejection pulse PD1 having the first shrinkage element ES1, the first shrinkage maintenance element ER1, the second shrinkage element ES2, the second shrinkage maintenance element ER2, and the expansion element EE as described above, the ejection amount can be kept constant over a wide range of viscosity by adjusting the viscosity correction ratio (V1 / V2) of the ink.

[0111] When the viscosity shown in the viscosity information DV is the first viscosity ve1, the ratio (V1 / V2) corresponding to the target ejection amount β is the first value va1. When the viscosity shown in the viscosity information DV is the second viscosity ve2, which is higher than the first viscosity ve1, the ratio (V1 / V2) corresponding to the target ejection amount β is the second value va2, which is lower than the first value va1. When the viscosity shown in the viscosity information DV is the third viscosity ve3, which is higher than the second viscosity ve2, the ratio (V1 / V2) corresponding to the target ejection amount β is the third value va3, which is lower than the second value va2.

[0112] exist Figure 7 The example illustrates the first viscosity ve1, second viscosity ve2, third viscosity ve3, first value va1, second value va2, and third value va3 under the target ejection rate β. Figure 7 In the example shown, the first viscosity ve1 is about 2.3 mPa·s, the second viscosity ve2 is about 4.4 mPa·s, the third viscosity ve3 is about 6.7 mPa·s, the first value va1 is about 0.67, the second value va2 is about 0.25, and the third value va3 is about 0.

[0113] In this way, by decreasing the ratio (V1 / V2) of the first potential change V1 to the second potential change V2 as the viscosity shown by the viscosity information DV increases, it is possible to reduce the variation in ejection volume caused by the increase in liquid viscosity and suppress unstable ejection across a wider viscosity variation range of the liquid. In other words, by increasing the ratio (V1 / V2) of the first potential change V1 to the second potential change V2 as the viscosity shown by the viscosity information DV decreases, it is possible to reduce the variation in ejection volume caused by the increase in liquid viscosity and suppress unstable ejection across a wider viscosity variation range of the liquid. The following is based on... Figures 8 to 11 The calibration example for the ejection pulse PD1 is explained. It should be noted that the following example mainly focuses on adjusting the ratios (V1 / V2) and (V3 / V2), but it is not limited to this method. In addition to adjusting the ratios (V1 / V2) and (V3 / V2), other parameters such as ejection volume and ejection speed can also be adjusted.

[0114] Figure 8 This is an explanatory diagram of the ejection pulse PD1, or ejection pulse PD1-1, when the viscosity shown in the viscosity information DV is the first viscosity ve1. Ejection pulse PD1-1 is based on the aforementioned... Figure 5 As described, it 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.

[0115] Here, by setting the sum of the duration of the first contraction element ES1 and the duration of the first contraction maintenance element ER1, that is, the duration t1 from the start of the first contraction element ES1 to the start of the second contraction element ES2, to be approximately equal to 1 / 2 of the inherent vibration period (Tc) of the ejection section 50, the second contraction element ES2 can be weakened by the vibration based on the first contraction element ES1.

[0116] 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 times or more and 0.7 times or less of the natural vibration period (Tc) of the ejection portion 50, more preferably 0.4 times or more and 0.6 times or less of the natural vibration period (Tc) of the ejection portion 50. Therefore, it is preferable to use the vibration based on the first contraction element ES1 to reduce the vibration based on the second contraction element ES2. As a result, the correction width of the ejection amount based on the ratio of the first potential change V1 to the second potential change V2 can be increased.

[0117] Furthermore, by setting the sum of the duration of the second shrinkage element ES2 and the duration of the second shrinkage maintenance element ER2, i.e., the duration t2 from the beginning of the second shrinkage element ES2 to the end of the second shrinkage maintenance element ER2, to be approximately equal to the inherent vibration period (Tc) of the ejection section 50, it is possible to achieve the effect of damping the residual vibration of the ink in the pressure chamber C after the ink is ejected through the second shrinkage element ES2.

[0118] From this perspective, the period t2 from the beginning 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 of the natural vibration period (Tc) of the ejection section 50, more preferably 0.9 times or more and 1.1 times or less of the natural vibration period (Tc) of the ejection section 50. This suppresses residual vibration of the ink in the pressure chamber C after ink is ejected through the second contraction element ES2, thereby shortening the ink ejection time interval or suppressing the reduction of subsequent ink ejection characteristics.

[0119] Figure 9 This is an explanatory diagram of the ejection pulse PD1, or ejection pulse PD1-2, when the viscosity shown in the viscosity information DV is the second viscosity ve2. Ejection pulse PD1-2, like the aforementioned ejection 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.

[0120] The ratio (V1 / V2) in the ejection pulse PD1-2 is less than the ratio (V1 / V2) in the aforementioned ejection pulse PD1-1. Therefore, the ejection volume when the viscosity shown in the viscosity information DV is the second viscosity ve2 can be made close to the ejection volume when the viscosity shown in the viscosity information DV is the first viscosity ve1.

[0121] exist Figure 9In the example shown, the first potential change V1 in the ejection pulse PD1-2 is less than the first potential change V1 in the ejection pulse PD1-1. Here, it is preferable that the second potential change V2 when the viscosity shown in the viscosity information DV is the first viscosity ve1, and the second potential change V2 when the viscosity shown in the viscosity information DV is the second viscosity ve2, are equal to each other. Therefore, it is possible to preferably reduce the variation in ejection volume caused by an increase in the viscosity of the liquid.

[0122] It should be noted that, correspondingly, the second potential change V2 in the ejection pulse PD1-2 is greater than the second potential change V2 in the ejection pulse PD1-1, just as the first potential change V1 in the ejection pulse PD1-2 is less than the first potential change V1 in the ejection pulse PD1-1. That is, the ratio (V1 / V2) can be changed in such a way that the sum of the first potential change V1 and the second potential change V2 does not change.

[0123] Figure 10 This is an explanatory diagram of ejection pulse PD1, or ejection pulse PD1-3, when the viscosity shown in the viscosity information DV is the third viscosity ve3. Ejection pulse PD1-3 has a second contraction element ES2, a second contraction maintenance element ER2, and an expansion element EE, but lacks the first contraction element ES1 and the first contraction maintenance element ER1. Because it lacks the first contraction element ES1 and the first contraction maintenance element ER1, the vibration based on the second contraction maintenance element ER2 is not weakened. It should be noted that the ratio (V1 / V2) of ejection pulse PD1-3 without the first contraction element ES1 and the first contraction maintenance element ER1 is 0, and the ratio (V1 / V2) in ejection pulse PD1-3 is less than the ratio (V1 / V2) in the aforementioned ejection pulse PD1-2.

[0124] Figure 11 This is an explanatory diagram of another example of a jet pulse PD1, namely jet pulse PD1-4, where the viscosity shown in the viscosity information DV is higher than the third viscosity ve3. Like jet pulse PD1-3, jet pulse PD1-4 does not have the first contraction element ES1 and the first contraction maintenance element ER1. Instead, jet pulse PD1-4 has the first expansion element EE1 and the expansion maintenance element EM0. That is, jet pulse PD1-4 has the first expansion element EE1, the expansion maintenance element EM0, the second contraction element ES2, the second contraction maintenance element ER2, and the expansion element EE, but lacks the first contraction element ES1 and the first contraction maintenance element ER1.

[0125] The first expansion element EE1 undergoes a potential change with a third potential change amount V3 before the second contraction element ES2 to expand the pressure chamber C. 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, insufficient ejection volume can be suppressed even when the viscosity of the liquid is higher. Therefore, ejection pulses PD1-4 can also be used when the viscosity shown in the viscosity information DV is a fourth viscosity higher than the third viscosity ve3. In this case, the adjustment can also be made as follows: as the viscosity shown in the viscosity information DV increases, the ratio (V3 / V2) of the third potential change amount V3 to the second potential change amount V2 is increased.

[0126] Here, by setting the sum of the duration of the first expansion element EE1 and the duration of the expansion maintenance element EM0, i.e., the duration t3 from the start of the first expansion element EE1 to the start of the second contraction element ES2, to be approximately equal to 1 / 2 of the inherent vibration period (Tc) of the ejection section 50, the reversal of vibration and the timing of contraction overlap, thus having the advantage of easily ensuring the ejection volume and ejection speed.

[0127] 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 of the natural vibration period (Tc) of the ejector portion 50, more preferably 0.4 times or more and 0.6 times or less of the natural vibration period (Tc) of the ejector portion 50. Therefore, even with higher liquid viscosity, insufficient ejection volume can be effectively suppressed.

[0128] As described above, in this embodiment, by reducing the ratio (V1 / V2) of the first potential change V1 to the second potential change V2 as the viscosity shown by the viscosity information DV increases, it is possible to reduce the variation in the amount of ejection caused by the increase in the viscosity of the liquid and suppress unstable ejection over a wider viscosity variation range of the liquid.

[0129] B: Second Implementation Method

[0130] Hereinafter, a second embodiment of the present disclosure will be described. In the following examples, for elements that have the same function as those in the first embodiment, the reference numerals used in the description of the first embodiment will be retained, and detailed descriptions of each will be omitted as appropriate.

[0131] This embodiment is the same as the first embodiment, except that the waveform of the ejected pulse is different.

[0132] Figure 12This is an explanatory diagram of the ejection pulse PD3-1 in the second embodiment, where the viscosity shown in the viscosity information DV is the first viscosity ve1. The ejection pulse PD3-1 is the same as the ejection 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, the ejection pulse PD3-1 sequentially includes 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.

[0133] The first expansion element EE1 undergoes a potential change with a third potential change V3 before the first contraction element ES1, causing the pressure chamber C to expand. 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 is slightly pulled into the nozzle N just before ejection, thereby stabilizing the meniscus of the liquid in the nozzle N. As a result, deviations in ejection volume or ejection velocity can be reduced.

[0134] Here, the third potential change V3 is not particularly limited, for example, it is about 0.2×(V1+V2).

[0135] Furthermore, by adding the first contraction element ES1 at a timing that resonates with the vibration generated by the first expansion element EE1, and then adding the second contraction element ES2 at a timing that does not resonate with the vibration of the first contraction element ES1, i.e., at 1 / 2 of the inherent vibration period (Tc) of the ejection section 50, it is preferable that the vibration based on the second contraction element ES2 is weakened by the vibration based on the first contraction element ES1, so that even if the viscosity of the ink is low, the desired amount of ink can be ejected stably.

[0136] 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 of the natural vibration period (Tc) of the ejector portion 50, more preferably 0.4 times or more and 0.6 times or less of the natural vibration period (Tc) of the ejector portion 50. This allows for efficient liquid ejection.

[0137] Figure 13This is an explanatory diagram of the ejection pulse PD3-2 when the viscosity shown in the viscosity information DV in the second embodiment is the second viscosity ve2. The ejection pulse PD3-2 is the same as the ejection pulse PD3-1 described above, and has, in sequence, 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.

[0138] The ratio (V1 / V2) in the ejection pulse PD3-2 is less than the ratio (V1 / V2) in the aforementioned ejection pulse PD3-1. Therefore, the ejection volume when the viscosity shown in the viscosity information DV is a second viscosity ve2 higher than the first viscosity ve1 can be made close to the ejection volume when the viscosity shown in the viscosity information DV is the first viscosity ve1.

[0139] exist Figure 13 In the example shown, the first potential change V1 in the ejected pulse PD3-2 is less than the first potential change V1 in the ejected pulse PD3-1. Correspondingly, the second potential change V2 in the ejected pulse PD3-2 is greater than the second potential change V2 in the ejected pulse PD3-1, such that the sum of the first potential change V1 and the second potential change V2 remains unchanged. That is, the ratio (V1 / V2) is changed in such a way that the sum of the first potential change V1 and the second potential change V2 does not change.

[0140] It should be noted that, alternatively, the second potential change V2 when the viscosity shown in the viscosity information DV is the first viscosity ve1 and the second potential change V2 when the viscosity shown in the viscosity information DV is the second viscosity ve2 can be equal to each other. In this case, the variation in the ejection volume caused by the increase in the viscosity of the liquid can be preferably reduced.

[0141] Figure 14 This is an explanatory diagram of the ejection pulse PD3-3 when the viscosity shown in the viscosity information DV in the second embodiment is the third viscosity ve3. The ejection pulse PD3-3 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, but does not have the first contraction element ES1 and the first contraction maintenance element ER1.

[0142] Figure 15This is an explanatory diagram of another example of the ejection pulse PD3-4, where the viscosity shown in the viscosity information DV in the second embodiment is the third viscosity ve3. Like ejection pulse PD3-3, ejection pulse PD3-4 does not have the first contraction element ES1 and the first contraction maintenance element ER1. Instead, ejection pulse PD3-4 has a second expansion element EE2 and a second expansion maintenance element EM2. That is, ejection pulse PD3-4 has the first expansion element EE1, the expansion maintenance element EM0, the second expansion element EE2, the second expansion maintenance element EM2, the second contraction element ES2, the second contraction maintenance element ER2, and the expansion element EE, but lacks the first contraction element ES1 and the first contraction maintenance element ER1.

[0143] The second expansion element EE2, preceding the first expansion element EE1, undergoes a potential change with a fourth potential change amount V4 to expand the pressure chamber C. 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, insufficient ejection volume can be suppressed even when the liquid viscosity is higher. Therefore, it is also possible to use ejection pulse PD3-4 when the viscosity shown in the viscosity information DV is a fourth viscosity higher than the third viscosity ve3. In this case, the adjustment can also be made as follows: as the viscosity shown in the viscosity information DV increases, the ratio (V4 / V2) of the fourth potential change amount V4 to the second potential change amount V2 is increased.

[0144] From the viewpoint of high-efficiency ejection, it is preferable that the starting timing of the first expansion element EE1 is at the timing of resonance with the vibration generated by the second expansion element EE2, that is, after a period approximately equal to the natural vibration period (Tc) of the ejection section 50 from the beginning of the second expansion element EE2. Specifically, the period t5 from the beginning of the second expansion element EE2 to the beginning of the first expansion element EE1 is preferably 0.8 times or more and 1.2 times or less of the natural vibration period (Tc) of the ejection section 50, more preferably 0.9 times or more and 1.1 times or less of the natural vibration period (Tc) of the ejection section 50.

[0145] Furthermore, it is preferable that the starting timing of the second contraction element ES2 is the same as the timing of the vibration resonance based on the first expansion element EE1, that is, after a period approximately equal to 1 / 2 of the natural vibration period (Tc) of the ejection portion 50 from the beginning of the first expansion element EE1. In other words, the period t6 from the beginning of the first expansion element EE1 to the beginning of the second contraction element ES2 is preferably 0.3 times or more and 0.7 times or less of the natural vibration period (Tc) of the ejection portion 50, more preferably 0.4 times or more and 0.6 times or less of the natural vibration period (Tc) of the ejection portion 50.

[0146] The second embodiment described above can also reduce the variation in ejection volume caused by the increase in liquid viscosity and suppress unstable ejection within a wider viscosity variation range of the liquid.

[0147] C: Variation

[0148] The methods in the examples above can be varied. The following examples illustrate specific variations of the aforementioned methods. Methods chosen arbitrarily from the following examples can be appropriately combined without contradicting each other.

[0149] C1: Variation Example 1

[0150] The foregoing method exemplifies how to obtain viscosity information DV based on vibration information NVT, temperature information DT, and input information DY, but is not limited to this method. For example, viscosity information DV can also be based on at least one of vibration information NVT, temperature information DT, and input information DY.

[0151] C2: Variation Example 2

[0152] The foregoing method exemplifies the use of a check pulse PD2 to detect residual vibration, but it is not limited to this method. Residual vibration can also be detected using an ejector pulse PD1 as a check pulse. That is, the ejector pulse PD1 can also serve as a "check pulse".

[0153] C3: Variation Example 3

[0154] The foregoing method exemplifies the transmission of the ejection pulse PD1 and the check pulse PD2 using a single signal line, but it is not limited to this method; the ejection pulse PD1 and the check pulse PD2 can also be transmitted using separate transmission lines. Furthermore, the drive signal Com can also include signals or pulses other than the ejection pulse PD1 and the check pulse PD2.

[0155] C4: Variation Example 4

[0156] Among the foregoing embodiments, a serial liquid ejection device 100 is exemplified in which the conveyor 141 equipped with the head 151 reciprocates. However, this disclosure can also be applied to a row-type liquid ejection device in which multiple nozzles N are distributed across the full width of the medium M.

[0157] C5: Variation Example 5

[0158] The liquid ejection apparatus 100 exemplified in the foregoing embodiments can be used in various devices besides those specifically designed for printing, such as fax machines and copiers; the application of this disclosure is not particularly limited. However, the application of the liquid ejection apparatus is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of color material is used as a manufacturing apparatus for color filters in display devices such as liquid crystal display panels. Furthermore, a liquid ejection apparatus that ejects a solution of conductive material is used as a manufacturing apparatus for wiring and electrodes in wiring substrates. Additionally, for example, a liquid ejection apparatus that ejects a solution of organic matter related to living organisms is used as a manufacturing apparatus for biochips.

[0159] D: Appendix

[0160] The following is a summary of this publication.

[0161] (Appendix 1) A first embodiment of the liquid ejection device of this disclosure comprises: an ejection unit having a nozzle, a pressure chamber, and a piezoelectric element, wherein the nozzle ejects liquid, the pressure chamber is connected to the nozzle, and the piezoelectric element is driven according to a supplied drive signal to cause pressure fluctuation in the liquid within the pressure chamber; a drive signal generation circuit for generating the drive signal; an acquisition unit for acquiring viscosity information, the viscosity information representing the viscosity of the liquid; and a control unit for controlling the operation of the drive signal generation circuit, the drive signal including an ejection pulse that causes droplets to be ejected from the nozzle, the ejection pulse having: a first contraction element with a first potential change amount A potential change is performed to cause the pressure chamber to contract; a first contraction maintaining element is connected to the terminal of the first contraction element and maintains the terminal potential of the first contraction element; and a second contraction element is connected to the terminal of the first contraction maintaining element and performs a potential change with a second potential change to cause the pressure chamber to contract. When the viscosity shown in the viscosity information is a first viscosity, the ratio of the first potential change to the second potential change is a first value. When the viscosity shown in the viscosity information is a second viscosity higher than the first viscosity, the ratio of the first potential change to the second potential change is a second value less than the first value.

[0162] In the above method, by reducing the ratio of the first potential change to the second potential change as the viscosity information shows that the viscosity increases, it is possible to reduce the variation in ejection volume caused by the increase in liquid viscosity and suppress unstable ejection over a wider viscosity variation range of the liquid.

[0163] (Appendix 2) In a second embodiment, which is a preferred example of the first embodiment, when the viscosity shown in the viscosity information is a third viscosity higher than the second viscosity, the ejection pulse has the second contraction element but not the first contraction element and the first contraction maintenance element. In the above embodiments, when the viscosity of the liquid is too high, unstable ejection can be preferably suppressed by reducing unwanted micro-vibrations.

[0164] (Appendix 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 ejection pulse has: a first expansion element that undergoes a potential change with a third potential change amount before the second contraction element to expand the pressure chamber; 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 embodiments, even when the viscosity of the liquid is higher, insufficient ejection volume can be suppressed.

[0165] (Appendix 4) In the fourth embodiment, which is a preferred example of a third-party method, 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 inherent vibration period of the ejector portion. In the above embodiments, even when the viscosity of the liquid is higher, insufficient ejection volume can be suppressed with high efficiency.

[0166] (Appendix 5) In a fifth embodiment, which is a preferred example of the first embodiment, the ejection pulse has: a first expansion element that undergoes a potential change by a third potential change before the first contraction element to expand the pressure chamber; and a first expansion sustaining 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. In the above embodiments, the meniscus of the liquid within the nozzle before ejection can be stabilized, resulting in a reduction of deviations in ejection volume or ejection velocity.

[0167] (Appendix 6) In a 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 of the inherent vibration period of the ejector portion. In the above embodiments, liquid can be ejected with high efficiency.

[0168] (Appendix 7) In a seventh embodiment, which is a preferred example of the fifth embodiment, when the viscosity shown in the viscosity information is a third viscosity that is higher than the second viscosity, the ejection pulse has the second contraction element but not the first contraction element and the first contraction maintenance element. In the above embodiments, when the viscosity of the liquid is too high, unstable ejection can be preferably suppressed by reducing unwanted micro-vibrations.

[0169] (Appendix 8) In the eighth embodiment, which is a preferred example of the fifth embodiment, when the viscosity shown in the viscosity information is a third viscosity higher than the second viscosity, the ejection pulse has: a second expansion element that undergoes a potential change before the first expansion element to cause the pressure chamber to expand; 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 embodiments, even when the viscosity of the liquid is higher, insufficient ejection volume can be suppressed.

[0170] (Appendix 9) In the ninth embodiment, which is a preferred example of any one of the first to eighth embodiments, the change in the second potential when the viscosity shown in the viscosity information is the first viscosity is equal to the change in the second potential when the viscosity shown in the viscosity information is the second viscosity. In the above embodiments, it is preferable to reduce the variation in the amount of liquid ejected due to the increase in the viscosity of the liquid.

[0171] (Appendix 10) In the tenth embodiment, which is a preferred example of any one 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 of the natural vibration period of the ejection portion. In the above embodiments, the vibration based on the first contraction element can be reduced by the second contraction element. As a result, the correction width of the ejection amount based on the ratio of the first potential change to the second potential change can be increased.

[0172] (Appendix 11) In the eleventh embodiment, a preferred example of any one of the first to tenth embodiments, the liquid ejection device further includes a detection circuit that acquires an electrical signal representing the residual vibration of the liquid in the pressure chamber after the piezoelectric element imparts a pressure change to the liquid in the pressure chamber. The acquisition unit acquires the viscosity information based on the electrical signal. In the above embodiments, viscosity information can be acquired even without adding components such as a temperature sensor.

[0173] (Appendix 12) In a twelfth embodiment, which is a preferred example of any one of the first to tenth embodiments, the liquid ejection device further includes a temperature sensor that detects a temperature, and the acquisition unit acquires the viscosity information based on the detected temperature of the temperature sensor. In the above embodiments, viscosity information showing the viscosity change accompanying the temperature change of the liquid can be directly acquired.

[0174] (Appendix 13) In the thirteenth embodiment, which is a preferred example of any one of the first to tenth embodiments, the liquid dispensing device further includes a receiving unit that receives input from a user, and the acquiring unit acquires the viscosity information based on the receiving result of the receiving unit. In the above embodiments, viscosity information corresponding to the user's desire can be acquired.

Claims

1. A liquid ejection device, characterized in that, have: The ejection section has a nozzle, a pressure chamber, and a piezoelectric element. The nozzle ejects liquid, the pressure chamber is connected to the nozzle, and the piezoelectric element is driven according to a supplied drive signal to cause pressure changes in the liquid inside the pressure chamber. A drive signal generation circuit generates the drive signal; The acquisition unit acquires viscosity information, which represents the viscosity of the liquid; as well as The control unit controls the operation of the drive signal generation circuit. The drive signal includes an ejection pulse that causes droplets to be ejected from the nozzle. The ejection pulse has the following characteristics: The first contraction element causes the pressure chamber to contract by changing the potential with a first potential change amount. A first contraction-maintaining element is connected to the terminal of the first contraction element and maintains the terminal potential of the first contraction element. as well as The second contraction element is connected to the terminal of the first contraction maintenance element, and undergoes a potential change with a second potential change to cause the pressure chamber to contract. When the viscosity shown in the viscosity information is a first viscosity, the ratio of the first potential change to the second potential change is a first value. When the viscosity shown in the viscosity information is a second viscosity that is higher than the first viscosity, the ratio of the first potential change to the second potential change is a second value that is less than the first value.

2. The liquid ejection device according to claim 1, characterized in that, When the viscosity shown in the viscosity information is a third viscosity that is higher than the second viscosity, the ejection pulse has the second contraction element but not the first contraction element and the first contraction maintenance element.

3. The liquid ejection device according to claim 2, characterized in that, When the viscosity shown in the viscosity information is the third viscosity. The ejection pulse has the following characteristics: The first expansion element, preceding the second contraction element, undergoes a potential change with a third potential change to cause the pressure chamber to expand; and An expansion-maintaining element maintains the terminal potential of the first expansion element from its end to the beginning of the second contraction element.

4. The liquid ejection device according to claim 3, characterized in that, The period from the start of the first expansion element to the start of the first contraction element is more than 0.3 times and less than 0.7 times the natural vibration period of the ejection portion.

5. The liquid ejection device according to claim 1, characterized in that, The ejection pulse has the following characteristics: The first expansion element, preceding the first contraction element, undergoes a potential change with a third potential change to cause the pressure chamber to expand; and The first expansion sustaining element maintains the terminal potential of the first expansion element from its end to the beginning of the first contraction element.

6. The liquid ejection device according to claim 5, characterized in that, The period from the start of the first expansion element to the start of the first contraction element is more than 0.3 times and less than 0.7 times the natural vibration period of the ejection portion.

7. The liquid ejection device according to claim 5, characterized in that, When the viscosity shown in the viscosity information is a third viscosity that is higher than the second viscosity, the ejection pulse has the second contraction element but not the first contraction element and the first contraction maintenance element.

8. The liquid ejection device according to claim 5, characterized in that, When the viscosity shown in the viscosity information is a third viscosity that is higher than the second viscosity, The ejection pulse has the following characteristics: A second expansion element undergoes a potential change prior to the first expansion element to cause the pressure chamber to expand; and The second expansion sustaining element maintains the terminal potential of the second expansion element from its terminal to the beginning of the first expansion element.

9. The liquid ejection device according to claim 1, characterized in that, The change in the second potential when the viscosity shown in the viscosity information is the first viscosity is equal to the change in the second potential when the viscosity shown in the viscosity information is the second viscosity.

10. The liquid ejection device according to claim 1, characterized in that, The period from the start of the first contraction element to the start of the second contraction element is more than 0.3 times and less than 0.7 times the natural vibration period of the ejection portion.

11. The liquid ejection device according to claim 1, characterized in that, The liquid ejection device also includes a detection circuit that acquires an electrical signal. This electrical signal indicates the residual vibration of the liquid in the pressure chamber after the pressure change, imparted by the piezoelectric element. The acquisition unit acquires the viscosity information based on the electrical signal.

12. The liquid ejection device according to claim 1, characterized in that, The liquid ejection device also includes a temperature sensor that detects the temperature. The acquisition unit acquires the viscosity information based on the detection temperature of the temperature sensor.

13. The liquid ejection device according to claim 1, characterized in that, The liquid dispensing device also includes a receiving unit, which accepts input from the user. The acquisition unit acquires the viscosity information based on the acceptance result of the acceptance unit.

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