Piezoelectric nozzle droplet volume control method, device, storage medium and printer

Abstract

The present invention discloses a piezoelectric nozzle droplet volume control method, device, storage medium, and printer. In this 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 based on the jet velocity curve, thereby achieving the goal of balancing precision and efficiency in the electronic additive manufacturing process. The method includes: determining a single droplet forming jet velocity range; determining a jet velocity curve corresponding to a target number of single droplets based on 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.

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. Driven by an external actuation waveform, it can achieve picoliter-scale material dispensing. Using droplets as the primary material deposition point, controlled inkjet printhead motion and droplet ejection can create two-dimensional patterns or three-dimensional structures of functional materials. Due to its advantages, such as high material deposition accuracy, good controllability, broad material compatibility, and low cost, piezoelectric inkjet printing is being applied not only to flat-panel printing but also to the additive manufacturing of multi-material functional electronic devices, such as printed electronics, bioprinting, solar cells, and other applications. In these emerging applications, material deposition accuracy and efficiency are conflicting characteristics. Small droplet sizes enable high-precision material formation but result in reduced formation efficiency, while large droplet sizes enable high-efficiency material deposition but cannot achieve high-precision material patterning. Balancing this tension between manufacturing accuracy and efficiency is a pressing technical challenge for inkjet-based additive manufacturing.

[0003] Currently, on-demand control of droplet size in inkjet printing through multi-droplet fusion is the primary approach to balancing manufacturing efficiency and precision. Specifically, small droplets are used at the edges of the printed pattern to ensure a highly precise outline of the material deposition pattern. Large droplets are used to efficiently fill areas within the printed pattern, improving the efficiency of the printed pattern. Based on the above analysis, on-demand control of droplet volume is key to achieving high-precision and high-efficiency jet formation in inkjet printing. This requires designing a drive waveform that matches the printhead's structural parameters with the ink's physical properties. Only a suitable actuation waveform can effectively control droplet volume. However, due to the lack of an effective mapping between droplet volume and drive waveform, existing waveforms for controlling droplet volume rely primarily on manual parameter adjustment. This not only suffers from long parameter adjustment cycles and poor droplet volume control accuracy, but also requires extensive experience in parameter adjustment. Furthermore, because material properties significantly influence droplet ejection performance, manual parameter adjustment is required for each functional material with varying physical properties. These factors severely limit the industrial application of inkjet technology in additive manufacturing of electronics. 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 this 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 droplets of a piezoelectric nozzle is provided, comprising:

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

[0007] Determining a jet velocity curve based on 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 dimensionless equation into the 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, jet velocity, viscosity of the sprayed material, density of the sprayed material, and surface tension of the sprayed material.

[0016] In some embodiments, the step of determining the minimum speed and the maximum speed according to the dimensionless equation 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, respectively, 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 based on 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 spraying material, the viscosity of the spraying material, the surface tension coefficient of the spraying material, and the diameter of the spray 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 pattern of jet velocity;

[0025] Determining 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 to-be-determined jet velocity 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; and 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 consistent with dynamic characteristics 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 finite time;

[0030] According to the target sine function and the weighted truncation function, the start time and the end time corresponding to the stage of extruding the sprayed material to form a jet are determined; according to the start time and the end time corresponding to the stage of extruding the sprayed material to form a jet, 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 includes:

[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, configured to determine a jet velocity curve based on 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;

[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 piezoelectric nozzle droplet volume control method, device, storage medium, and printer. In this 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 based on the jet velocity curve, thereby achieving the goal of balancing precision and efficiency in the electronic additive manufacturing process. The method includes: determining the single droplet forming jet velocity range; determining a jet velocity curve corresponding to a target number of single droplets based on 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 in accordance with 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 specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

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

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

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

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

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

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

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

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

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

[0053] Figure 10 A schematic diagram illustrating jet velocity curves corresponding to desired droplet volumes of 120 pL and 180 pL provided in accordance with some embodiments is exemplified;

[0054] Figure 11 A schematic diagram illustrating an iterative approximation process of a jet velocity curve corresponding to desired droplet volumes of 120 pL and 180 pL provided in accordance with some embodiments is shown;

[0055] Figure 12 A schematic diagram exemplarily illustrates a driving voltage waveform and experimental phenomena for a desired droplet volume of 120 pL provided in accordance with some embodiments;

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

[0057] Figure 14 The following is a schematic structural diagram of a piezoelectric nozzle droplet volume control device according to some embodiments;

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

[0059] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although 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. Rather, 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 related technologies, the driving voltage waveform for regulating droplet volume mainly relies on manual parameter adjustment. This has the following drawbacks: (1) Long parameter adjustment cycle: 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 capture system, and the waveform parameters (including jump edge, hold 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 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 generate additional pressure oscillations in the ink, causing disturbances to the jet process, resulting in reduced printing accuracy and jetting efficiency; (4) 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 used to drive 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 droplet volume of a piezoelectric nozzle according to some embodiments is exemplarily shown, and the method includes S100-S300.

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

[0064] In the embodiments of the present application, precise control of droplet volume is required to improve printing accuracy. If the desired droplet volume is the sum of the volumes of multiple single droplets, then multiple single droplets must be able to merge to form a large droplet. This requires that the single droplets formed earlier have a lower falling velocity, while the single droplets formed later have a higher falling velocity. Only in this way can the fusion of multiple single droplets be completed before being deposited on the substrate to obtain droplets of the desired droplet volume. Based on this, to control the falling velocity of a single droplet, it is necessary to know the single droplet forming jet velocity range, that is, the maximum velocity and minimum velocity, and control the falling velocity of the single droplet within this single droplet forming jet velocity range.

[0065] In some embodiments, Figure 2 A flowchart of another method for controlling droplet volume of a piezoelectric nozzle is exemplarily shown according to 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 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, where the stationary droplet refers to a droplet with 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 dimensionless equation can be expressed as:

[0068]

[0069] Where 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, R n and R t is the principal radius of curvature at the droplet interface.

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

[0071] In the embodiment 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 droplets of a piezoelectric nozzle is exemplarily shown according to some embodiments. The step of converting the dimensional 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 an embodiment of the present application, according to the similarity theory, the NS equation (i.e., a dimensionless 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 embodiments of this application, the scale and time effects of the droplet formation process refer to the spatial geometric dimensions of the piezoelectric nozzle. A single nozzle orifice in a piezoelectric nozzle typically has a size range of 5 to 120 μm, so the scale effect indicates that droplet formation occurs on a scale of tens of microns. Time refers to the duration from ejection to formation of a single droplet. A piezoelectric nozzle takes approximately 10 to 60 μs to extrude and form a droplet, so the time effect indicates that the droplet formation process occurs within tens of microseconds.

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

[0077] In the embodiment of the present application, the physical quantity in the dimensioned equation is divided by the characteristic physical quantity to obtain the corresponding dimensionless 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 brought 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 the minimum speed and the 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 droplets 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 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 generation law of the inkjet droplet (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 single droplet generation, the intermediate variables corresponding to the formation mode can be determined through parameter regression. For example, an MJ-AL-80 piezoelectric nozzle can be used. In this case, 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 present embodiment, under the critical conditions for satellite droplet formation, the droplet formation process for high-surface-tension ink materials also exhibits high similarity, and corresponding intermediate variables can also be determined through parameter regression. For example, using an MJ-AL-80 piezoelectric nozzle, the regression yields values ​​of A and B of approximately 0.0914 and 0.462, respectively. This means that 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, respectively, 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] For example, 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] For example, 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. The second actual values ​​corresponding to the first intermediate variable and the second intermediate variable 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 based on 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 based on 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 nozzle hole diameter.

[0096] For any jettable material, according to the definition of its dimensionless Weber number and Reynolds number, the droplet formation process at the nozzle orifice gradually evolves with the increase of 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 jet velocity is shown as follows: Figure 6 shown. Figure 6 In the left figure, curve 2 represents the droplet formation process under the critical condition of producing micro-droplets. At this time, the corresponding jet velocity is just enough to 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 is just enough to prevent the formation of 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. Let the jet velocities corresponding to curves 2 and 4 be v respectively. 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, respectively, and their values ​​can be expressed as:

[0097]

[0098] Formula (3) corresponds to the minimum velocity, and formula (4) corresponds to the maximum velocity. Here, 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 nozzle. Therefore, for any functional spray material, the jet velocity range corresponding to single droplet formation can be determined according to the above formula, thus laying a theoretical foundation for subsequent droplet volume control.

[0099] S200. Determine a jet velocity curve based on 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, that is, the target number, V Ds It is the minimum single droplet volume, that is, 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 injection material (density, viscosity, surface tension) are the determining factors that determine the morphology of the injection 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 injection 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 ) onto a time-varying velocity curve 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 desired 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. The step of determining the time-varying law of the jet velocity in step S201 includes:

[0106] According to the first preset constraint, the target sine function is determined, and the first preset constraint 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 squeezes the internal fluid to generate 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] A weighted truncation function is determined based on a second preset constraint, which states that the jet velocity corresponding to a single droplet must be controlled for a limited time. This limitation can be understood as the piezoelectric nozzle can only produce a single droplet in a single layer under a single voltage waveform. The printing process requires depositing multiple droplets, and the voltage waveform must be repeatedly applied to the piezoelectric nozzle structure. Therefore, the voltage waveform for a single injection must be effective within a limited time (typically the time required to form a single droplet), and the corresponding jet velocity must also be maintained within the effective time. If the duration is too long, multiple droplets cannot be ejected.

[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 flow 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, 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) to consider the pressure wave vibration characteristics (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 as follows: Figure 7 As 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 jet formation stage of the extruded ejection material is determined. s and end time t e .

[0112] The normalization coefficient α is determined 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. 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 (re-absorption of ink to accelerate jet breakage). The droplet graphics corresponding to the three stages are shown as follows: 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] Where, t s and t e are the start time and end time of stage II, i.e., the start time and end time corresponding to the stage of extruding the ejected material to form a jet.

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

[0117] In the embodiment of the present application, the key to achieving droplets of the desired droplet volume by merging multiple single droplets is that multiple ejected single droplets can merge with each other to form large droplets. This requires that the single droplets formed in the 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 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 peaks (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 is to be determined.

[0121] S203 , obtaining a jet velocity curve based on 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 with each other to form large droplets. This requires that the single droplet formed in the front has a low falling velocity, while the single droplet formed in the back has a high falling velocity, and can complete the fusion of multiple droplets 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 compounded 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 target number of droplets that need to be fused.

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

[0126] In the embodiments of this application, droplet volume control requires only controlling the target number of jet velocity curves, achieving precise multi-stage droplet size control to obtain droplets of the desired droplet volume. This overcomes the limitations of traditional droplet volume control, which often results in low precision through manual adjustment of waveform parameters. Jet velocity curve design constructs a multi-peak composite jet velocity curve within the single droplet forming jet velocity range, enabling droplet fusion. Ultimately, volume control is achieved by controlling the number of fused droplets.

[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 includes:

[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 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 based on 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 when input into the nozzle injection model for the first time 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. Based on the deviation between the two, an iterative learning algorithm is used to determine the change value of the driving voltage vector. The driving voltage vector originally input to the nozzle injection model is corrected using the change value, and the corrected driving voltage vector is then continued to be input into the nozzle injection model. 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 a detailed implementation of the iterative algorithm, please refer to the patent disclosure of CN202210451257.3. The equivalent circuit model in this disclosure is the nozzle injection model used in the embodiments of this application. In some embodiments, the modified drive voltage waveform must comply with preset constraints. Specifically, the preset constraints are that the drive voltage vector determined at the start time (time 0) is equal to the drive voltage vector determined at the final time, where the final time is the final time required to form a droplet of the desired droplet volume.

[0132] In the embodiments of this application, the iteratively calculated drive voltage waveform parameters have a continuous and smooth shape, overcoming the impact of traditional trapezoidal pulse voltage waveforms and significantly extending the service life of the printhead structure. Furthermore, by controlling the shape of the jet velocity curve, the embodiments of this application can effectively suppress pressure fluctuations while achieving droplet volume control, significantly improving droplet ejection efficiency and jet stability, which is of great significance for improving manufacturing efficiency.

[0133] Regarding the previous embodiment, let's describe it in a different way. After designing the jet velocity curve, 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 based on 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 discrete number of vectors 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 patent disclosure of CN202210451257.3. 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 Figure 9 As shown, in Figure 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 the time n 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, i.e., η(0)=η(N) in formula (10), i.e., 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 then input into the nozzle injection model, and the above process is repeated until the iteration converges. Figure 9 The iterative process shown can calculate the driving voltage waveform corresponding to the jet velocity at all times in 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 embodiments of this application, by designing a jet velocity curve, the corresponding drive voltage waveform can be automatically calculated. The iterative calculation of the waveform parameters automatically matches the material properties, enabling precise control of the droplet volume of the sprayed material. The iterative optimization calculation uses the designed desired jet velocity curve as the optimization target and iteratively calculates the drive voltage waveform corresponding to that jet velocity.

[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 the curve is used as the 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 characteristics of the injection material to determine the satellite droplet jet velocity range; 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, so as to control the volume by controlling the number of droplet fusions; the iterative optimization calculation uses 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 thereof is regulated on demand.

[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 nozzle diameter. Therefore, for a nozzle with a diameter of 80μm, the single droplet volume 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 as follows: Figure 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. Figure 11 The iterative process of the jet velocity corresponding to 120pL and 180pL droplets is demonstrated. After 250 steps of iteration, 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 this application.

[0142] Through the above iterative calculation, the driving voltage waveform corresponding to the desired jet velocity curve can be obtained, which is used as the driving input of the piezoelectric nozzle to achieve precise control of the droplet volume. Figure 12 The figure shows the driving voltage waveform corresponding to a 120pL droplet volume. After using this voltage waveform to drive the piezoelectric nozzle, the measured droplet volume is 113.31pL, with a relative error of 5.57% in volume control. Figure 13 The figure shows the voltage waveform corresponding to a droplet volume of 180 pL. After using this voltage waveform to drive the piezoelectric nozzle, the measured droplet volume is 182.77 pL, 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 this 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 this method, the jet velocity range for forming a single droplet is determined, and a jet velocity curve is designed based on the jet velocity range for forming a single droplet. 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 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 Figure 14 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 based on 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 configured 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. 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 via 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] Figure 15 A schematic structural diagram 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 Figure 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 configured to execute the program 410, and specifically to execute the relevant steps in the above-mentioned embodiment of the power transmission line fault monitoring method.

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

[0157] Processor 402 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments 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 will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing device, centralized on a single computing device, or distributed across a network of multiple computing devices. Alternatively, they can be implemented using program code executable by a computing device, which can then be stored in a storage device and executed by the computing device. In some cases, the steps shown or described can be performed in a different order than that shown, or can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0160] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A piezoelectric nozzle droplet volume control method, characterized in that: include: Determine the velocity range of the single droplet forming jet; Determining a jet velocity curve based on 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; determining a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve; 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: determining a dimensional equation for describing a process from a single droplet being ejected from the nozzle to forming a stationary droplet based on a momentum conservation equation, wherein the stationary droplet refers to a droplet with a velocity of zero; 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; and determining the minimum velocity and the maximum velocity based on the dimensionless equation; According to the dimensionless equation, the step of determining the minimum speed and the maximum speed includes: 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 a single droplet; determining second 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; substituting the first actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively 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; determining a formula corresponding to the minimum speed based on 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 diameter; determining a formula corresponding to the maximum speed based on 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 nozzle diameter; The step of determining a jet velocity curve based on the single droplet forming jet velocity range and the desired droplet volume comprises: determining a time-varying law of the jet velocity; determining a jet velocity to be determined corresponding to each single droplet in the target number of single droplets based on the target number and the single droplet forming jet velocity range; and obtaining a jet velocity curve based on the jet velocity to be determined corresponding to each single droplet in the target number of single droplets and the time-varying law. 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 the target sine function according to a first preset constraint condition, the first preset constraint condition is to conform to the dynamic characteristics of the process of ejecting the injection material; determining the weighted truncation function according to a second preset constraint condition, the second preset constraint condition is that the jet velocity corresponding to a single droplet is controlled to last within a finite time; determining the start time and end time corresponding to the stage of extruding the injection material to form a jet according to the target sine function and the weighted truncation function; determining the normalization coefficient according to the start time and end time corresponding to the stage of extruding the injection material to form a jet, as well as the target sine function and the weighted truncation function.

2. The method according to claim 1, characterized in that The step of converting the dimensionless equation into the 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, jet velocity, viscosity of the sprayed material, density of the sprayed material, and surface tension of the sprayed material.

3. 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 includes: 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.

4. 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, configured to determine a jet velocity curve based on 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; a conversion unit, configured to determine a driving voltage waveform for driving the piezoelectric nozzle based on the jet velocity curve; 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: determining a dimensional equation for describing a process from a single droplet being ejected from the nozzle to forming a stationary droplet based on a momentum conservation equation, wherein the stationary droplet refers to a droplet with a velocity of zero; 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; and determining the minimum velocity and the maximum velocity based on the dimensionless equation; According to the dimensionless equation, the step of determining the minimum speed and the maximum speed includes: 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 a single droplet; determining second 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; substituting the first actual values ​​corresponding to the first intermediate variable and the second intermediate variable respectively 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; determining a formula corresponding to the minimum speed based on 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 diameter; determining a formula corresponding to the maximum speed based on 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 nozzle diameter; The step of determining a jet velocity curve based on the single droplet forming jet velocity range and the desired droplet volume comprises: determining a time-varying law of the jet velocity; determining a jet velocity to be determined corresponding to each single droplet in the target number of single droplets based on the target number and the single droplet forming jet velocity range; and obtaining a jet velocity curve based on the jet velocity to be determined corresponding to each single droplet in the target number of single droplets and the time-varying law. 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 the target sine function according to a first preset constraint condition, the first preset constraint condition is to conform to the dynamic characteristics of the process of ejecting the injection material; determining the weighted truncation function according to a second preset constraint condition, the second preset constraint condition is that the jet velocity corresponding to a single droplet is controlled to last within a finite time; determining the start time and end time corresponding to the stage of extruding the injection material to form a jet according to the target sine function and the weighted truncation function; determining the normalization coefficient according to the start time and end time corresponding to the stage of extruding the injection material to form a jet, as well as the target sine function and the weighted truncation function.

5. A storage medium storing at least one executable instruction, wherein the executable instruction enables a processor to execute the piezoelectric nozzle droplet volume control method according to any one of claims 1 to 3.

6. 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; 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 to 3.

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