Piezoelectric nozzle liquid drop volume regulation and control method and device, storage medium and printer

Abstract

The invention discloses a piezoelectric spray head liquid drop volume regulation and control method and device, a storage medium and a printer, and the method comprises the steps: determining a single liquid drop forming jet velocity range, designing a jet velocity curve based on the single liquid drop forming jet velocity range, and obtaining liquid drops with expected liquid drop volume through the jet velocity curve, and then the driving voltage waveform used for driving the piezoelectric spray head is determined according to the jet velocity curve, and the purpose of balancing the precision and efficiency in the electronic additive manufacturing process can be achieved. The method comprises the following steps: determining a single droplet forming jet velocity range; determining a jet velocity curve corresponding to a target number of single droplets according to the single droplet forming jet velocity range and an expected droplet volume; wherein the expected liquid drop volume is the total volume of the target number of single liquid drops; and determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

Description

Technical Field

[0001] The present invention relates to the field of piezoelectric inkjet technology, and in particular to a piezoelectric inkjet head droplet volume control method, device, storage medium and printer. Background Art

[0002] Piezoelectric inkjet is a commonly used material deposition technology in additive manufacturing processes. It can achieve picoliter-level material distribution under the drive of an external actuation waveform. The jet droplets are used as the basic material deposition point. By controlling the movement of the inkjet print head and the droplet ejection, a two-dimensional pattern or three-dimensional structure of functional materials can be constructed. Due to the advantages of piezoelectric inkjet printing technology such as high material deposition accuracy, good controllability, wide material compatibility and low cost, piezoelectric inkjet printing technology is not only used in flat photo printing, but also in the additive manufacturing process of multi-material functional electronic devices, such as printed electronics, bioprinting, solar cells and some other applications. In these emerging applications, the deposition accuracy and efficiency of materials are a pair of contradictory characteristics. Small-sized droplets can achieve high-precision material forming, but lead to reduced forming efficiency; large-sized droplets can achieve high-efficiency material deposition, but cannot achieve high-precision material patterning deposition. How to balance the contradiction between manufacturing accuracy and efficiency is a technical problem that the current inkjet-based additive manufacturing technology urgently needs to overcome.

[0003] At present, the on-demand control of droplet size in inkjet printing through multi-droplet fusion is the main way to balance manufacturing efficiency and precision. That is, for the edge position of the printed pattern, small-sized droplets are used to ensure that the material deposition pattern has a high-precision contour edge; for the area inside the printed pattern that needs to be filled with high efficiency, large-sized droplets are used for efficient filling to improve the forming efficiency of the printed pattern. Based on the above analysis, the on-demand control of droplet volume is the key to the inkjet printing technology to achieve high-precision and high-efficiency injection forming. It is necessary to combine the print head structure parameters and the physical properties of the ink to match the drive waveform design. Only a suitable actuation waveform can achieve effective control of the droplet volume. However, due to the lack of an effective mapping relationship between the droplet volume and the drive waveform, the existing waveform for controlling the droplet volume mainly relies on manual parameter adjustment, which not only has the defects of long parameter adjustment cycle and poor droplet volume control accuracy, but also requires the parameter adjustment personnel to have rich experience accumulation. In addition, since the material properties will significantly affect the droplet ejection performance, manual parameter adjustment is required for each functional material with different physical properties. These factors seriously limit the industrial application of inkjet technology in electronic additive manufacturing processes. Summary of the invention

[0004] In view of this, the present invention provides a piezoelectric nozzle droplet volume control method, device, storage medium and printer. In the method, the single droplet forming jet velocity range is determined, and the jet velocity curve is designed based on the single droplet forming jet velocity range. The jet velocity curve can accurately control the droplet volume, and then the driving voltage waveform for driving the piezoelectric nozzle is determined according to the jet velocity curve. This can solve the problem of balancing precision and efficiency in the electronic additive manufacturing process and promote the industrial application of piezoelectric inkjet printing technology in the additive manufacturing of electronic devices.

[0005] According to one aspect of the present invention, a method for controlling the volume of a droplet of a piezoelectric nozzle is provided, comprising:

[0006] Determine the velocity range of the single droplet forming jet;

[0007] Determine a jet velocity curve according to the single droplet forming jet velocity range and the desired droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the desired droplet volume is the sum of the volumes of the target number of single droplets;

[0008] Based on the jet velocity curve, a driving voltage waveform for driving the piezoelectric nozzle is determined.

[0009] In some embodiments, the single droplet forming jet velocity range includes a minimum velocity and a maximum velocity, the piezoelectric nozzle includes a nozzle, and the step of determining the single droplet forming jet velocity range includes:

[0010] Based on the momentum conservation equation, a dimensioned equation is determined for describing a process in which a single droplet is ejected from the nozzle and forms a stationary droplet, wherein the stationary droplet refers to a droplet with zero velocity;

[0011] Converting the dimensional equation into a dimensionless equation, wherein the dimensionless equation includes a first intermediate variable, a second intermediate variable, a Weber number, and a Reynolds number;

[0012] From the dimensionless equation, the minimum and maximum velocities are determined.

[0013] In some embodiments, the step of converting the dimensioned equation into a dimensionless equation comprises:

[0014] Selecting characteristic physical quantities; wherein the characteristic physical quantities include nozzle diameter, jet velocity, viscosity of the injection material, density of the injection material and surface tension of the injection material;

[0015] The dimensioned equation is converted into a dimensionless equation using the nozzle hole diameter, the jet velocity, the viscosity of the spray material, the density of the spray material and the surface tension of the spray material.

[0016] In some embodiments, according to the dimensionless equation, the step of determining the minimum speed and the maximum speed comprises:

[0017] Based on the critical state of generating a single droplet, determining first actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively through parameter regression;

[0018] Based on the critical state of generating satellite droplets, second actual values ​​corresponding to the first intermediate variable and the second intermediate variable are determined by parameter regression;

[0019] Substituting first actual values ​​corresponding to the first intermediate variable and the second intermediate variable into the dimensionless equation to form a first curve with the Weber number as the abscissa and the Reynolds number as the ordinate;

[0020] Substituting the second actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively into the dimensionless equation to form a second curve with the Weber number as the abscissa and the Reynolds number as the ordinate;

[0021] Determine a formula corresponding to the minimum speed according to the first curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material and the nozzle hole diameter;

[0022] A formula corresponding to the maximum speed is determined according to the second curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material and the diameter of the nozzle hole.

[0023] In some embodiments, the step of determining a jet velocity curve according to the single droplet forming jet velocity range and the desired droplet volume comprises:

[0024] Determine the time-varying law of the jet velocity;

[0025] Determine the jet velocity to be determined corresponding to each single droplet in the target number of single droplets according to the target number and the single droplet forming jet velocity range;

[0026] The jet velocity curve is obtained by combining the jet velocity to be determined corresponding to each single droplet in the target number of single droplets and the time-varying law.

[0027] In some embodiments, the time-varying law of the jet velocity includes a target sine function, a weighted truncation function, and a normalization coefficient; the step of determining the time-varying law of the jet velocity includes:

[0028] Determining a target sine function according to a first preset constraint condition, wherein the first preset constraint condition is in accordance with a dynamic characteristic of a process of ejecting the sprayed material;

[0029] Determining a weighted truncation function according to a second preset constraint condition, wherein the second preset constraint condition is that the jet velocity corresponding to the single droplet is controlled to be continuous within a limited time;

[0030] According to the target sine function and the weighted truncation function, the start time and the end time corresponding to the jet formation stage of the extruded spray material are determined; according to the start time and the end time corresponding to the jet formation stage of the extruded spray material, as well as the target sine function and the weighted truncation function, the normalization coefficient is determined.

[0031] In some embodiments, the step of determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve comprises:

[0032] Using the nozzle spray model, determine the jet velocity output by the nozzle spray model;

[0033] According to the jet velocity and the jet velocity curve output by the nozzle injection model, an iterative learning algorithm is used to determine a driving voltage waveform for driving the piezoelectric nozzle.

[0034] According to another aspect of the present invention, a piezoelectric nozzle droplet volume control device is provided, comprising:

[0035] A first determining unit is used to determine a single droplet forming jet velocity range;

[0036] A second determining unit is used to determine a jet velocity curve according to the single droplet forming jet velocity range and the expected droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the expected droplet volume is the sum of the volumes of the target number of single droplets;

[0037] The conversion unit is used to determine a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

[0038] According to another aspect of the present invention, a storage medium is provided, wherein the storage medium stores at least one executable instruction, and the executable instruction enables a processor to execute the piezoelectric nozzle droplet volume control method as described above.

[0039] According to another aspect of the present invention, there is provided a printer, comprising: a piezoelectric nozzle, a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus;

[0040] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the piezoelectric nozzle droplet volume control method as described above.

[0041] The present invention provides a method, device, storage medium and printer for controlling the volume of droplets of a piezoelectric nozzle. In the method, a single droplet forming jet velocity range is determined, and a jet velocity curve is designed based on the single droplet forming jet velocity range. Droplets of desired droplet volume can be obtained through the jet velocity curve, and the droplet volume can be precisely controlled. Then, a driving voltage waveform for driving the piezoelectric nozzle is determined according to the jet velocity curve, so as to achieve the purpose of balancing the accuracy and efficiency in the electronic additive manufacturing process. The method comprises: determining a single droplet forming jet velocity range; determining a jet velocity curve corresponding to a target number of single droplets according to the single droplet forming jet velocity range and the desired droplet volume; wherein the desired droplet volume is the total volume of the target number of single droplets; and determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

[0042] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0044] Figure 1 A flowchart of a piezoelectric nozzle droplet volume control method provided according to some embodiments is exemplarily shown;

[0045] Figure 2 A flowchart of another method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments;

[0046] Figure 3 A flowchart of another method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments;

[0047] Figure 4 A flowchart of another method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments;

[0048] Figure 5 A schematic diagram for verifying the similarity of generating a single droplet in a critical state according to some embodiments is exemplarily shown;

[0049] Figure 6A schematic diagram exemplarily shows a single droplet forming spraying condition provided according to some embodiments;

[0050] Figure 7 A schematic diagram of a single droplet forming jet velocity curve provided according to some embodiments is exemplarily shown;

[0051] Figure 8 A schematic diagram of a jet velocity curve related to a desired droplet volume provided according to some embodiments is exemplarily shown;

[0052] Fig. 9 A schematic diagram exemplarily shows a principle of iterative calculation of a jet velocity curve corresponding to a driving voltage waveform provided in accordance with some embodiments;

[0053] Fig.10 A schematic diagram showing a jet velocity curve corresponding to a desired droplet volume of 120 pL and 180 pL provided in accordance with some embodiments is exemplified;

[0054] Fig.11 A schematic diagram showing an iterative approximation process of a jet velocity curve corresponding to a desired droplet volume of 120 pL and 180 pL provided in accordance with some embodiments;

[0055] Fig.12 A schematic diagram showing a driving voltage waveform and experimental phenomena of a desired droplet volume of 120 pL provided in accordance with some embodiments;

[0056] Fig.13 A schematic diagram illustrating a driving voltage waveform and experimental phenomena for a desired droplet volume of 180 pL provided according to some embodiments is exemplified.

[0057] Fig.14 The schematic diagram of the structure of a piezoelectric nozzle droplet volume control device provided according to some embodiments is exemplarily shown;

[0058] Fig.15 A schematic diagram of the structure of a terminal provided according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0059] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0060] In the related art, the driving voltage waveform for regulating the droplet volume mainly relies on manual parameter adjustment. It has the following defects: (1) Long parameter adjustment cycle: In order to reduce the number of parameters to be adjusted, manual parameter adjustment usually adopts a multi-pulse driving waveform. The droplet formation process is repeatedly observed through the droplet shooting system, and the waveform parameters (including jump edge, holding time, voltage amplitude, etc.) are adjusted until the desired droplet volume is achieved. The parameter adjustment process takes a lot of time to obtain relatively ideal waveform parameters. (2) High parameter adjustment cost: The manual parameter adjustment process requires the use of a droplet jet visualization measurement system, which is not required in the inkjet printing process. It requires the jet system to have additional integrated functional components, resulting in excessively high equipment costs and difficulty in being widely used in industrial production. (3) Low parameter adjustment accuracy: In order to reduce the number of parameters to be adjusted, manual parameter adjustment uses a multi-pulse composite driving voltage waveform. This type of waveform drives the piezoelectric nozzle and produces significant structural vibration. On the one hand, it will reduce the service life of the print head. On the other hand, it will produce additional pressure oscillations in the ink, causing disturbances to the jet process, resulting in reduced printing accuracy and jetting efficiency. (4) High difficulty in parameter adjustment: The manual parameter adjustment process requires technicians to have rich parameter adjustment experience, and the parameter adjustment effects obtained by different personnel are different. It is difficult to quickly obtain stable waveform parameters with consistent jetting performance through manual parameter adjustment. (5) Poor maintainability: The functional ink used for inkjet printing is usually a nanoparticle suspension, and its material properties will change slowly over time. After the properties change, the manual parameter adjustment process needs to be repeated.

[0061] In order to solve the above technical problems, an embodiment of the present application provides a piezoelectric nozzle droplet volume control method, in which the method determines the single droplet forming jet velocity range and designs a jet velocity curve based on the single droplet forming jet velocity range. Droplets of desired droplet volume can be obtained through the jet velocity curve, thereby achieving precise control of the droplet volume. Then, the driving voltage waveform for driving the piezoelectric nozzle is determined according to the jet velocity curve, thereby achieving the purpose of balancing the precision and efficiency in the electronic additive manufacturing process.

[0062] Figure 1 A flow chart of a method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments, and the method includes S100-S300.

[0063] S100, determining a single droplet forming jet velocity range.

[0064] In the embodiment of the present application, in order to improve the printing accuracy, it is necessary to accurately control the droplet volume. If the desired ejected droplet volume is the sum of the volumes of multiple single droplets, then multiple ejected single droplets need to be able to merge with each other to form a large droplet. This requires that the single droplets formed in the front have a lower falling speed, while the single droplets formed in the back have a higher falling speed, so that multiple single droplets can be merged before being deposited on the substrate to obtain droplets of the desired droplet volume. Based on this, to control the falling speed of a single droplet, it is necessary to know the single droplet forming jet velocity range, that is, the maximum velocity and the minimum velocity, and control the falling speed of the single droplet within the single droplet forming jet velocity range.

[0065] In some embodiments, Figure 2 A flowchart of another piezoelectric nozzle droplet volume control method provided according to some embodiments is exemplarily shown. The single droplet forming jet velocity range includes a minimum velocity and a maximum velocity, the piezoelectric nozzle includes a nozzle, and the step of determining the single droplet forming jet velocity range includes S101-S103.

[0066] S101. Based on the momentum conservation equation, determine a dimensioned equation for describing a process from a single droplet being ejected from the nozzle to forming a stationary droplet, wherein the stationary droplet refers to a droplet having a zero velocity.

[0067] Specifically, since the process from a single droplet being ejected from the nozzle to forming a stationary droplet can be described by the momentum conservation equation (i.e., the NS equation), the dimensioned equation can be expressed as:

[0068]

[0069] In the formula, u i is the velocity field tensor, x i or x j is the spatial dimension tensor, t is time, p is pressure, ρ is the density of the ejected material, μ is the viscosity of the ejected material, σ is the surface tension coefficient of the ejected material, and R n and R t is the principal radius of curvature at the droplet interface. Exemplarily, the ejected material may be ink.

[0070] S102. Convert the dimensional equation into a dimensionless equation, wherein the dimensionless equation includes a first intermediate variable, a second intermediate variable, a Weber number, and a Reynolds number.

[0071] In the embodiments of the present application, when calculating the velocity range of the single droplet forming jet, it is proposed to use dimensionless numbers to describe the forming characteristics of the single droplet. The numerical value of the dimensionless number is independent of the selected unit and can better reflect the forming characteristics of the single droplet.

[0072] In some embodiments, Figure 3 The flowchart of another method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments. The step of converting the dimensioned equation into a dimensionless equation includes S1021-S1022.

[0073] S1021. Select characteristic physical quantities; wherein the characteristic physical quantities include nozzle diameter, jet velocity, viscosity of the injection material, density of the injection material, and surface tension of the injection material.

[0074] In the embodiment of the present application, according to the similarity theory, the NS equation (i.e., a dimensional equation) can be converted into a dimensionless NS equation (i.e., a dimensionless equation) by selecting a set of characteristic physical quantities. Combined with the scale and time effects of the droplet formation process during inkjet printing, the nozzle diameter d0, jet velocity v0, ink viscosity μ0, density ρ0, and surface tension coefficient σ0 are selected as characteristic physical quantities.

[0075] In the embodiment of the present application, in the scale and time effect of the droplet formation process, the scale refers to the spatial geometric size of the piezoelectric nozzle. The single nozzle structure of the piezoelectric nozzle is generally in the range of 5 to 120 μm, so the scale effect refers to the droplet generation occurring at a scale of tens of microns. Time refers to the duration from the injection to the formation of a single droplet. It takes about 10 to 60 μs for the piezoelectric nozzle to squeeze and form a droplet, so the time effect is that the droplet formation process occurs within the range of tens of microseconds.

[0076] S1022. Convert the dimensionless equation into a dimensionless equation by using the nozzle diameter, the jet velocity, the viscosity of the injection material, the density of the injection material, and the surface tension of the injection material.

[0077] In the embodiment of the present application, the corresponding dimensionless quantity can be obtained by dividing the physical quantity in the dimensioned equation by the characteristic physical quantity, that is:

[0078] Among them, the superscript symbol "0" marks the dimensionless quantity corresponding to the relevant physical quantity. According to the mathematical representation of the above dimensionless quantity, it is substituted into equation (1) and the NS equation can be converted into a dimensionless equation by replacing the relevant physical quantity, that is:

[0079]

[0080] Wherein, A and B are intermediate variables composed of dimensionless quantities, wherein A is the first intermediate variable, B is the second intermediate variable, We is the Weber number, and Re is the Reynolds number.

[0081] S103: Determine a minimum speed and a maximum speed according to the dimensionless equation.

[0082] In the embodiment of the present application, the dimensionless equation can reflect the formation characteristics of a single droplet, so the velocity range of the single droplet formation jet can be obtained based on the dimensionless equation analysis.

[0083] In some embodiments, Figure 4 The flowchart of another method for controlling the volume of a droplet of a piezoelectric nozzle is exemplarily shown according to some embodiments. The step of determining the minimum speed and the maximum speed according to the dimensionless equation includes S1031-S1036.

[0084] S1031. Based on the critical state of generating a single droplet, determine the first actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively through parameter regression.

[0085] Since the dimensionless quantity is the ratio of the physical quantity to the characteristic physical quantity, the intermediate variable actually describes the law of inkjet droplet generation (not specific to the corresponding scale, representing a liquid flow pattern), that is, when the single droplet formation process of any ink is similar, the intermediate variables are basically equal. In the critical state of just producing a single droplet, that is, the process of ink ejecting from the nozzle and forming a stationary droplet (droplet velocity is zero) has a high degree of similarity. This means that for different injection materials, under the critical conditions of producing a single droplet, the intermediate variables are basically the same. This conclusion has been verified by multiphase flow numerical simulation. The simulation (fitting equation) and model results (CFD) are as follows Figure 5 shown.

[0086] For the critical state of generating a single droplet, the intermediate variable corresponding to the forming mode can be determined by parameter regression. For example, an MJ-AL-80 piezoelectric nozzle can be used, and the values ​​of the intermediate variables A and B are approximately 0.1625 and 0.7529, respectively, that is, the first actual value corresponding to the first intermediate variable is 0.1625, and the first actual value corresponding to the second intermediate variable is 0.7529.

[0087] S1032. Based on the critical state of generating satellite droplets, determine second actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively through parameter regression;

[0088] In the embodiment of the present application, under the critical condition of just generating satellite droplets, for the ink material with high surface tension coefficient, the droplet forming process also has a high degree of similarity, and the corresponding intermediate variables can also be determined by parameter regression. For example, an MJ-AL-80 piezoelectric nozzle can be used, and the values ​​of A and B obtained by regression are approximately 0.0914 and 0.462, respectively, that is, the second actual value corresponding to the first intermediate variable is 0.0914, and the second actual value corresponding to the second intermediate variable is 0.462.

[0089] S1033. Substitute the first actual values ​​corresponding to the first intermediate variable and the second intermediate variable into the dimensionless equation to form a first curve with the Weber number as the horizontal coordinate and the Reynolds number as the vertical coordinate.

[0090] Exemplarily, based on the example of step S1031, the first actual value corresponding to the first intermediate variable is 0.1625, and the first actual value corresponding to the second intermediate variable is 0.7529. Figure 3 As shown, a first curve, namely, curve 2, is formed.

[0091] S1034. Substitute the second actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively into the dimensionless equation to form a second curve with the Weber number as the horizontal coordinate and the Reynolds number as the vertical coordinate.

[0092] Exemplarily, the second actual value corresponding to the first intermediate variable obtained in the example of step S1032 is 0.0914, and the second actual value corresponding to the second intermediate variable is 0.462. Figure 3 As shown, a second curve, namely, curve 4, is formed.

[0093] because Figure 3 The second curve in is obtained by substituting the second actual values ​​corresponding to the first intermediate variable and the second intermediate variable, respectively, and the second actual values ​​corresponding to the first intermediate variable and the second intermediate variable, respectively, are calculated based on the high surface tension coefficient injection material. Considering that the high surface tension coefficient material is more likely to form satellite droplets than the low surface tension system material, within this critical condition, the high surface tension system injection material will not produce satellite droplets, and the low surface tension coefficient ink material will not produce satellite droplets. Therefore, the area between the two sets of critical conditions can be used as the single droplet forming area, such as Figure 3 As shown, in Figure 3 The middle region II represents the single droplet formation region, that is, the region enclosed by curves 2 and 4.

[0094] S1035. Determine a formula corresponding to the minimum speed according to the first curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material, and the nozzle hole diameter.

[0095] S1036: Determine a formula corresponding to the maximum speed according to the second curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material, and the diameter of the nozzle hole.

[0096] For any jettable material, according to the definition of the two dimensionless numbers of Weber number and Reynolds number, the droplet formation process at the nozzle orifice gradually evolves with the increase of the jet velocity, from no droplet formation corresponding to a small jet velocity to the formation of satellite droplets corresponding to a large jet velocity. The evolution of the droplet formation pattern with the jet velocity is shown in the following figure: Figure 6 shown. Figure 6 In the left figure, curve 2 represents the droplet formation process under the critical condition of producing microdroplets. At this time, the corresponding jet velocity can just make the ink form a stationary droplet; curve 4 represents the droplet formation process under the critical condition of producing satellite droplets. The corresponding jet velocity just does not form satellite droplets. In the area between curves 2 and 4, the corresponding jet velocity can form a single droplet, and the droplet velocity gradually increases from curve 2 to 4. Suppose the jet velocities corresponding to curves 2 and 4 are v min and v max , then v min and v max are the minimum and maximum thresholds of the jet velocity corresponding to the formation of a single droplet, and their values ​​can be expressed as:

[0097]

[0098] Formula (3) is the formula corresponding to the minimum speed, and formula (4) is the formula corresponding to the maximum speed, where ρ, μ, and σ are the density, viscosity, and surface tension coefficient of the spray material, respectively, and d is the nozzle diameter of the spray head. Therefore, for any functional spray material, the jet velocity range corresponding to the single droplet formation can be determined according to the above formula, thus laying a theoretical foundation for the subsequent droplet volume control.

[0099] S200. Determine a jet velocity curve according to the single droplet forming jet velocity range and the desired droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the desired droplet volume is the sum of the volumes of the target number of single droplets.

[0100] In the embodiment of the present application, the droplet volume control process can actually be completed by controlling the number of single droplets in the droplets that merge into the desired droplet volume, that is, the target number. Assume that the diameter of a single nozzle of the piezoelectric nozzle is d, and the volume of the single droplet formed by the spraying is V Ds =πd 3 / 6, the expected droplet volume at the piezoelectric nozzle can be expressed as:

[0101] V D =N D V Ds (5)

[0102] Where V D is the expected droplet volume, N D is the number of droplets that need to be fused, i.e. the target number, V Ds It is the minimum single droplet volume, i.e., the single droplet volume.

[0103] In the embodiment of the present application, the piezoelectric nozzle is driven by the internal piezoelectric actuator to finally stimulate the jet at the nozzle and form droplets. The jet velocity, nozzle diameter and the physical properties of the spray material (density, viscosity, surface tension) are the determining factors for the morphology of the spray droplets. For the single droplet formation process, the jet velocity range can be determined according to formulas (3) and (4). However, in the actual ink jetting process, the jet velocity is a time-varying velocity. Therefore, the jet velocity curve finally determined in the embodiment of the present application is a time-varying velocity curve. How to convert the jet velocity v j ∈(v min ,v max ) is mapped onto a time-varying velocity curve, which needs to be solved. In some embodiments, the step of determining the jet velocity curve according to the single droplet forming jet velocity range and the expected droplet volume includes:

[0104] S201. Determine the time-varying law of the jet velocity.

[0105] In some embodiments, the time-varying law of the jet velocity includes a target sine function, a weighted truncation function, and a normalization coefficient. S201 The step of determining the time-varying law of the jet velocity includes:

[0106] According to the first preset constraint condition, the target sine function is determined, and the first preset constraint condition is to meet the dynamic characteristics of the process of ejecting the injection material. The dynamic characteristics of the process of ejecting the injection material can be understood as the essence of the piezoelectric nozzle is that under the drive of the external voltage waveform, the piezoelectric ceramic structure undergoes a slight deformation, and the deformation amount is generally tens of nanometers. The deformation of the piezoelectric structure will squeeze the internal fluid to produce a pressure wave. The pressure wave propagates along the flow channel and drives the free droplet jet at the nozzle to produce droplets. The dynamic process mainly refers to the pressure wave oscillation process inside the nozzle. The jet velocity fluctuation at the nozzle should be as consistent as possible with the pressure wave oscillation period. The jet velocity curve designed in this way can be achieved by adjusting the piezoelectric waveform.

[0107] According to the second preset constraint, a weighted truncation function is determined, wherein the second preset constraint is that the jet velocity control corresponding to a single droplet is continuous within a limited time. The jet velocity control corresponding to a single droplet is continuous within a limited time, which can be understood as the piezoelectric nozzle can only produce a single layer of a single droplet under the excitation of a single voltage waveform. The printing process needs to deposit many droplets, and the voltage waveform needs to be repeatedly applied to the piezoelectric nozzle structure. Therefore, the voltage waveform of a single injection must act within a limited time (usually the time required to form a droplet), and the corresponding jet velocity must also be completed within the effective time. If the duration is too long, the injection of multiple droplets cannot be achieved.

[0108] In other words, an innovative formula is given in the embodiment of the present application to complete the jet velocity v jTo the time-varying jet velocity curve, that is:

[0109]

[0110] Where V j (t) is the time-varying jet velocity, v j is between the threshold v min and v max The jet velocity between the nozzle and the nozzle is the jet velocity between the nozzle and the nozzle, l is the structural length of the nozzle channel of a single nozzle, c is the pressure wave propagation speed of the ink, α a is the normalization coefficient. In this formula, the time-varying jet velocity actually consists of two parts, where v j describes the amplitude of the jet velocity, and ψ(t) describes the time-varying law of the jet velocity. In order to ensure that the designed jet velocity time-varying curve can be achieved by adjusting the driving waveform, ψ(t) must meet two constraints: one is the first preset constraint, that is, the time-varying law of ψ(t) must conform to the dynamic characteristics of the inkjet process, and the other is the second preset constraint, that is, the jet velocity must end within a limited time. For the first preset constraint, a sine function f1 is introduced into ψ(t) that takes into account the vibration characteristics of the pressure wave (the angular frequency describes the free vibration characteristics of the pressure wave in the nozzle); for the second preset constraint, a weighted truncation function f2 is introduced into ψ(t), and the jet velocity curve formed by the function is shown as follows: Figure 7 Shown in the middle left picture.

[0111] According to the target sine function and the weighted truncation function, the starting time t corresponding to the stage of extruding the ejected material to form a jet is determined. s and end time t e .

[0112] According to the start time and end time corresponding to the jet formation stage of the extrusion spray material, as well as the target sine function and the weighted truncation function, the normalization coefficient α is determined. a .

[0113] See again Figure 7 In the middle right figure, along the time axis, ψ(t) can be divided into three stages, namely stage I (ink absorption to form a concave liquid surface), stage II (rapid extrusion of ink to form a jet), and stage III (ink absorption again to accelerate jet breakage). The corresponding droplet graphics of the three stages are shown in Figure 1. Figure 7 As shown in the lower right corner. Since stage II provides the main jet kinetic energy for the formation of inkjet droplets, the average value of this stage can be mapped to the jet velocity v j ∈(v min ,v max ), thereby establishing a mapping relationship between the jet velocity corresponding to the single droplet formation and ψ(t). According to this relationship, the normalization coefficient α aIt is expressed as the following formula:

[0114]

[0115] In the formula, t s and t e They are the start time and end time of stage II, namely the start time and end time corresponding to the stage of extruding the sprayed material to form a jet.

[0116] S202, determining the jet velocity to be determined corresponding to the target number of single droplets according to the target number and the single droplet forming jet velocity range.

[0117] In the embodiments of the present application, the key to achieving droplets of expected droplet volume by merging multiple single droplets is that multiple sprayed single droplets can merge with each other to form large droplets, which requires that the single droplets formed in the front have a low falling speed, while the single droplets formed in the back have a high falling speed, so that the fusion of multiple single droplets can be completed before being deposited on the substrate.

[0118] In order to ensure that the formed single droplets can merge into a large droplet, the velocity of the droplet ejected later must be greater than the droplet ejected earlier, that is, the jet velocity corresponding to different peak values ​​(the jet velocity corresponding to different single droplets) should satisfy v min <v j (1)<…<v j (N D )<v max , in order to satisfy this constraint, the jet velocity v j The value of is realized by the equal distribution strategy, that is,

[0119]

[0120] where v j The jet velocity corresponding to a single droplet to be determined.

[0121] S203 , obtaining a jet velocity curve according to the jet velocity to be determined corresponding to each single droplet in the target number of single droplets and the time-varying law.

[0122] The key to achieving multi-droplet fusion is that multiple ejected single droplets can fuse together to form large droplets. This requires that the single droplets formed in front have a low falling velocity, while the single droplets formed in the back have a high falling velocity, so that the fusion of multiple droplets can be completed before being deposited on the substrate. To form this type of jet velocity, it is necessary to perform a secondary synthesis design of the jet velocity curve based on the jet velocity curve described by equation (6). To this end, in the embodiment of the present application, a multi-peak composite jet velocity curve is proposed, that is, the jet velocity curve described by equation (6) is composited in the time domain, such as Figure 8As shown, the jet velocity curve is obtained by combining, and its mathematical formula can be expressed as:

[0123]

[0124] Where V N (t) is the jet velocity that can achieve the desired droplet volume, that is, the jet velocity curve, i is the jet pulse index, ΔT is the time span of the single droplet jet velocity curve, N D is the number of droplets that need to be fused, i.e. the target number.

[0125] Through the above method, a jet velocity curve can be obtained. Subsequently, by designing a pressure-driven waveform so that the nozzle forms a jet velocity curve at the nozzle hole, droplets of the expected droplet volume can be obtained.

[0126] In the embodiment of the present application, the control of the droplet volume only needs to control the target number of the jet velocity curve, so that the droplet size can be precisely controlled at multiple levels to obtain droplets of the desired droplet volume, overcoming the limitation of low precision of droplet volume control caused by the traditional manual adjustment of waveform parameters. The jet velocity curve design is to construct a multi-peak composite jet velocity curve that can achieve droplet fusion within the single droplet forming jet velocity range, and finally control the volume by controlling the number of droplet fusions.

[0127] S300: Determine a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

[0128] In some embodiments, the step of determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve comprises:

[0129] Using the nozzle injection model, determine the jet velocity at time n output by the nozzle injection model;

[0130] According to the jet velocity at time n output by the nozzle injection model and the jet velocity at time n in the jet velocity curve, an iterative learning algorithm is used to determine a driving voltage waveform for driving the piezoelectric nozzle.

[0131] In the embodiment of the present application, after the jet velocity curve is designed, the key to realizing the droplet volume control is how to control the piezoelectric nozzle to realize the corresponding jet velocity, that is, to calculate the corresponding driving voltage waveform according to the jet velocity curve. The nozzle injection model is used to convert the driving voltage vector input therein into the jet velocity at n moments. The driving voltage vector for converting into the jet velocity that is first input into the nozzle injection model can be 0. The jet velocity output by the nozzle injection model is compared with the jet velocity in the jet velocity curve to determine the deviation between the two, and the iterative learning algorithm is used based on the deviation between the two to determine the change value of the driving voltage vector, and the driving voltage vector originally input into the nozzle injection model is corrected by using the change value, and then the corrected driving voltage vector is continuously input into the nozzle injection model, and the above process is repeated until the iteration converges. In the embodiment of the present application, the jet velocity at each moment in the jet velocity curve is converted into a driving voltage vector, and the driving voltage vectors obtained by converting the jet velocity at all moments are combined to form a driving voltage waveform vector, that is, a driving voltage waveform. For detailed iterative algorithm implementation, please refer to the patent disclosure of CN202210451257.3, in which the equivalent circuit model is the nozzle injection model in the embodiment of the present application. In some embodiments, the modified driving voltage waveform needs to meet the preset constraints, and the specific preset constraints are that the driving voltage vector determined at the start time (0 time) is equal to the driving voltage vector determined at the final time, and the final time is the final time required for the formation of a droplet of the desired droplet volume.

[0132] In the embodiment of the present application, the shape of the iteratively calculated driving voltage waveform parameters is continuous and smooth, which overcomes the impact effect of the traditional trapezoidal pulse voltage waveform and can significantly extend the working life of the print head structure. In the embodiment of the present application, by controlling the shape of the jet velocity curve, the pressure vibration can be effectively suppressed on the basis of droplet volume control, and the droplet ejection efficiency and jet stability can be significantly improved, which is of great significance for improving manufacturing efficiency.

[0133] For the previous embodiment, another description is given. After the jet velocity curve is designed, the key to achieving droplet volume control is how to control the piezoelectric nozzle to achieve the corresponding jet velocity, that is, to calculate the corresponding driving voltage waveform according to the jet velocity curve. This goal can be achieved using the mathematical equation described below:

[0134]

[0135] Where η(n) is the driving voltage vector at time n, V N (n) is the expected jet velocity at time n, V M(n) is the jet velocity output by the injection model at time n, and N is the vector discrete number within the time range of interest, which corresponds to the final moment mentioned in the previous embodiment. The key to the above equation is to establish an algorithm that can search for a set of voltage waveform vectors so that the jet velocity output by the nozzle continuously approaches the desired jet velocity. To this end, the embodiment of the present application proposes to use a two-dimensional iterative optimization algorithm to achieve this goal. For detailed iterative algorithm implementation, please refer to the CN202210451257.3 patent disclosure. The equivalent circuit model in the disclosure is the nozzle injection model in the embodiment of the present application. The iterative calculation principle is as follows Fig. 9 As shown, in Fig. 9 The driving voltage vector to be determined is input into the nozzle injection model, and the nozzle injection model outputs the jet velocity, that is, V M (n), then V M (n) and the expected jet velocity V at time n in the jet velocity curve N (n), the expected jet velocity V at this time N (n) is determined according to formula (9), and then the deviation E is calculated according to formula (10) q (k), based on the deviation E q (k) Using an iterative learning algorithm, the driving voltage vector is corrected. The correction must meet the preset constraints, that is, η(0)=η(N) in formula (10), that is, the driving voltage vector determined at the start time (time 0) is equal to the driving voltage vector determined at the final time. The corrected driving voltage vector is continuously input into the nozzle injection model, and the above process is repeated until the iteration converges. Fig. 9 The iterative process shown can calculate the driving voltage waveform corresponding to the jet velocity at all times of the jet velocity curve, and use it as the driving input of the piezoelectric nozzle to obtain droplets of desired droplet volume.

[0136] In the embodiment of the present application, by designing the jet velocity curve, the corresponding driving voltage waveform can be automatically calculated, and the iterative calculation process of the waveform parameters will automatically match the material properties, and the droplet volume control of the sprayed material can be accurately achieved. The iterative optimization calculation takes the designed desired jet velocity curve as the optimization target, and obtains the driving voltage waveform corresponding to the jet velocity through iterative calculation.

[0137] In the embodiment of the present application, by adjusting the number of peaks of the jet velocity curve, the jet velocity curve corresponding to different droplet volumes can be obtained, and it can be used as an iterative optimization target. The corresponding jet velocity can be quickly obtained through iterative learning, which solves the defects of the traditional manual parameter adjustment method in terms of cycle, cost, accuracy and maintainability, and can promote the reliability of the inkjet-based electronic additive manufacturing process. The method proposed in the present invention mainly includes three steps: single droplet forming jet velocity range calculation, jet velocity curve design, and iterative optimization calculation of the driving voltage waveform. Among them, the single droplet forming jet velocity range is mainly determined based on the physical property parameters of the injection material to determine the satellite droplet-free jet velocity range; the jet velocity curve design is to construct a multi-peak composite jet velocity curve that can realize droplet fusion within the single droplet forming jet velocity range, so as to control the volume by controlling the number of droplet fusions; the iterative optimization calculation takes the designed desired jet velocity curve as the optimization target, and obtains the driving voltage waveform corresponding to the jet velocity through iterative calculation.

[0138] In order to illustrate in detail the real-time process achieved by the method in the embodiment of the present application, UV (ultraviolet light curing) resin material is used as the experimental ink, and the droplet volume is regulated as needed.

[0139] First, the single droplet forming jet velocity range is calculated based on the physical properties of UV resin ink. The density, viscosity, surface tension and pressure wave propagation velocity of UV resin are 768kg / m 3 , 8.0cP, 0.028N / m, 1400m / s, using MJ-AL-80 piezoelectric nozzle, the nozzle diameter is 80μm, the single droplet forming jet velocity range is calculated to be v min =1.9087m / s, v max =2.3892m / s. This data provides a basis for designing the jet velocity curve corresponding to the expected droplet volume.

[0140] Secondly, the jet velocity curve is designed according to the single droplet forming jet velocity range. Usually, the size of the formed single droplet is basically equal to the diameter of the nozzle hole. Therefore, for a nozzle hole with a diameter of 80μm, the volume of a single droplet is about 60pL. If the desired droplet volume of 120pL and 180pL is to be achieved, the jet velocity curve can be designed according to the steps. The results are shown in the figure. Fig.10 shown.

[0141] Finally, the designed jet velocity curve is used as the iterative optimization target to calculate the driving voltage waveform corresponding to the desired jet velocity. Fig.11 The iterative process of the jet velocity corresponding to 120pL and 180pL droplets is demonstrated. After 250 iterations, the output jet velocity of the piezoelectric nozzle basically coincides with the expected jet velocity, proving the rationality of the jet velocity curve proposed in the embodiment of the present application.

[0142] Through the above iterative calculation, the driving voltage waveform corresponding to the desired jet velocity curve can be obtained, which can be used as the driving input of the piezoelectric nozzle to achieve precise control of the droplet volume. Fig.12 The figure shows the driving voltage waveform corresponding to a droplet volume of 120pL. After the piezoelectric nozzle is driven by this voltage waveform, the measured droplet volume is 113.31pL, and the relative error of volume control is 5.57%; Fig.13 The figure shows the voltage waveform corresponding to a droplet volume of 180pL. After the piezoelectric nozzle is driven by the voltage waveform, the measured droplet volume is 182.77pL, and the relative error of volume control is 1.54%. The experimental results prove the effectiveness and accuracy of the method proposed in the embodiment of the present application, which is of great significance for promoting the application of inkjet printing technology in electronic additive manufacturing.

[0143] An embodiment of the present application provides a method for controlling the droplet volume of a piezoelectric nozzle. In the method, a single droplet forming jet velocity range is determined, and a jet velocity curve is designed based on the single droplet forming jet velocity range. Droplets of desired droplet volume can be obtained through the jet velocity curve, thereby achieving precise control of the droplet volume. Then, a driving voltage waveform for driving the piezoelectric nozzle is determined according to the jet velocity curve, thereby achieving a balance between precision and efficiency in the electronic additive manufacturing process.

[0144] Furthermore, as a response to the above Figure 1 The embodiment of the present invention provides a piezoelectric nozzle droplet volume control device, such as Fig.14 As shown, including:

[0145] The first determining unit 1401 is used to determine the velocity range of the single droplet forming jet;

[0146] A second determining unit 1402 is configured to determine a jet velocity curve according to the single droplet forming jet velocity range and the desired droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the desired droplet volume is the sum of the volumes of the target number of single droplets;

[0147] The conversion unit 1403 is used to determine a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

[0148] According to one embodiment of the present invention, a storage medium is provided, wherein the storage medium stores at least one executable instruction, and the computer executable instruction can execute the piezoelectric nozzle droplet volume control method in any of the above method embodiments.

[0149] According to one embodiment of the present invention, a printer is provided, comprising: a piezoelectric nozzle, a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus;

[0150] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the piezoelectric nozzle droplet volume control method as described above.

[0151] Fig.15 A schematic diagram of the structure of a terminal provided according to an embodiment of the present invention is shown. The specific embodiment of the present invention does not limit the specific implementation of the terminal.

[0152] like Fig.15 As shown, the terminal may include: a processor (processor) 402 , a communication interface (Communications Interface) 404 , a memory (memory) 406 , and a communication bus 408 .

[0153] The processor 402 , the communication interface 404 , and the memory 406 communicate with each other via a communication bus 408 .

[0154] The communication interface 404 is used to communicate with other devices such as clients or other servers.

[0155] The processor 402 is used to execute the program 410, and specifically can execute the relevant steps in the above-mentioned power transmission line fault monitoring method embodiment.

[0156] Specifically, the program 410 may include program codes, which include computer operation instructions.

[0157] The processor 402 may be a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiment of the present invention. The one or more processors included in the terminal may be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.

[0158] The memory 406 is used to store the program 410. The memory 406 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0159] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0160] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the volume of a droplet of a piezoelectric nozzle, characterized in that: include: Determine the velocity range of the single droplet forming jet; Determine a jet velocity curve according to the single droplet forming jet velocity range and the desired droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the desired droplet volume is the sum of the volumes of the target number of single droplets; Based on the jet velocity curve, a driving voltage waveform for driving the piezoelectric nozzle is determined.

2. The method according to claim 1, characterized in that The single droplet forming jet velocity range includes a minimum velocity and a maximum velocity, the piezoelectric nozzle includes a nozzle, and the step of determining the single droplet forming jet velocity range includes: Based on the momentum conservation equation, a dimensioned equation is determined for describing a process in which a single droplet is ejected from the nozzle and forms a stationary droplet, wherein the stationary droplet refers to a droplet with zero velocity; Converting the dimensional equation into a dimensionless equation, wherein the dimensionless equation includes a first intermediate variable, a second intermediate variable, a Weber number, and a Reynolds number; From the dimensionless equation, the minimum and maximum velocities are determined.

3. The method according to claim 2, characterized in that The step of converting the dimensioned equation into a dimensionless equation comprises: Selecting characteristic physical quantities; wherein the characteristic physical quantities include nozzle diameter, jet velocity, viscosity of the injection material, density of the injection material and surface tension of the injection material; The dimensioned equation is converted into a dimensionless equation using the nozzle hole diameter, the jet velocity, the viscosity of the spray material, the density of the spray material and the surface tension of the spray material.

4. The method according to claim 2, characterized in that: According to the dimensionless equation, the steps of determining the minimum speed and the maximum speed include: Based on the critical state of generating a single droplet, determining first actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively through parameter regression; Based on the critical state of generating satellite droplets, second actual values ​​corresponding to the first intermediate variable and the second intermediate variable are determined by parameter regression; Substituting first actual values ​​corresponding to the first intermediate variable and the second intermediate variable into the dimensionless equation to form a first curve with the Weber number as the abscissa and the Reynolds number as the ordinate; Substituting the second actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively into the dimensionless equation to form a second curve with the Weber number as the abscissa and the Reynolds number as the ordinate; Determine a formula corresponding to the minimum speed according to the first curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material and the nozzle hole diameter; A formula corresponding to the maximum speed is determined according to the second curve, the density of the injection material, the viscosity of the injection material, the surface tension coefficient of the injection material and the diameter of the nozzle hole.

5. The method according to claim 1, characterized in that The step of determining a jet velocity curve according to the single droplet forming jet velocity range and the expected droplet volume comprises: Determine the time-varying law of the jet velocity; Determine the jet velocity to be determined corresponding to each single droplet in the target number of single droplets according to the target number and the single droplet forming jet velocity range; The jet velocity curve is obtained by combining the jet velocity to be determined corresponding to each single droplet in the target number of single droplets and the time-varying law.

6. The method according to claim 5, characterized in that The time-varying law of the jet velocity includes a target sine function, a weighted truncation function and a normalization coefficient; the step of determining the time-varying law of the jet velocity includes: Determining a target sine function according to a first preset constraint condition, wherein the first preset constraint condition is in accordance with a dynamic characteristic of a process of ejecting the sprayed material; Determining a weighted truncation function according to a second preset constraint condition, wherein the second preset constraint condition is that the jet velocity corresponding to the single droplet is controlled to be continuous within a limited time; According to the target sine function and the weighted truncation function, the start time and the end time corresponding to the jet formation stage of the extruded spray material are determined; according to the start time and the end time corresponding to the jet formation stage of the extruded spray material, as well as the target sine function and the weighted truncation function, the normalization coefficient is determined.

7. The method according to claim 1, characterized in that The step of determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve comprises: Using the nozzle spray model, determine the jet velocity output by the nozzle spray model; According to the jet velocity and the jet velocity curve output by the nozzle injection model, an iterative learning algorithm is used to determine a driving voltage waveform for driving the piezoelectric nozzle.

8. A piezoelectric nozzle droplet volume control device, characterized in that: include: A first determining unit is used to determine a single droplet forming jet velocity range; A second determining unit is used to determine a jet velocity curve according to the single droplet forming jet velocity range and the expected droplet volume; wherein the jet velocity curve includes the jet velocity corresponding to each single droplet in the target number of single droplets, and the expected droplet volume is the sum of the volumes of the target number of single droplets; The conversion unit is used to determine a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve.

9. A storage medium, wherein at least one executable instruction is stored in the storage medium, and the executable instruction enables a processor to execute the piezoelectric nozzle droplet volume control method according to any one of claims 1 to 7.

10. A printer, comprising: A piezoelectric nozzle, a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the piezoelectric nozzle droplet volume control method according to any one of claims 1-7.

Images