A method for improving the accuracy of inkjet printing based on molecular dynamics simulation

Abstract

The present invention discloses a method for improving the inkjet printing accuracy based on molecular dynamics simulation. Without changing the nozzle parameters and ink properties, only by optimizing the selection of the inkjet speed, the precise control of the inkjet droplet speed can be achieved by adjusting the heating rate or the deformation rate of the micro piezoelectric ceramic. This method uses molecular dynamics simulation software to simulate and analyze the droplet impact and spreading dynamics at the microscale, and obtains the relationship between the droplet spreading characteristics and the inherent parameters of the droplet itself at the micron or smaller scale of the inkjet droplet, making up for the defect that data cannot be obtained through experiments at this scale, and thereby obtaining a significant improvement in printing accuracy. Another method is also provided, which can change the ink properties and optimize the selection of the inkjet speed at the same time. By changing the material of the ink itself or adjusting the ratio, the parameters of the ink itself are changed, and the best matching coefficient is obtained, which can further improve the printing accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of improving the printing accuracy of inkjet printers, and more specifically, to a method for improving the inkjet printing accuracy based on molecular dynamics simulation. Background Art

[0002] In recent years, with the rapid development of inkjet printing technology, the application fields of printers have not been limited to large printing factories and office use. Small printers have increasingly entered households. Some small high-precision color inkjet printers have become the first choice for professional photographers or photography enthusiasts to print photos because of their convenience, small size, and satisfactory printing accuracy. With the development of related technologies in the inkjet printer manufacturing industry, new printers are smaller in size, faster in printing speed, and more convenient to use in applications. However, improving printing accuracy is an eternal topic because the most critical parameter for evaluating the quality of a printer is printing accuracy.

[0003] Although domestic and foreign scholars have made a large number of research achievements in improving inkjet printing accuracy, most of the existing improvement schemes focus on improving control accuracy or nozzle accuracy. Although these schemes can also achieve improvement effects, they will ultimately encounter bottlenecks due to the high technical costs brought about by accuracy improvement. Summary of the Invention

[0004] In view of this, aiming at the above-mentioned deficiencies in the existing technology, the present invention proposes a method for improving inkjet printing accuracy based on the dynamic characteristics of droplet impact on a solid surface at the microscopic scale of molecular dynamics simulation from the perspective of improving ink performance and inkjet speed to effectively solve the above problems.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a method for improving inkjet printing accuracy based on molecular dynamics simulation, which does not change the nozzle parameters and ink performance, but only optimizes the selection of inkjet speed. The specific steps include:

[0007] (a) Determine the inherent parameters of the inkjet nozzle of the corresponding printer according to the selected printer model;

[0008] (b) Calculate the diameter range of the inkjet droplets of the printer according to the corresponding printer accuracy parameters and inherent parameters;

[0009] (c) Obtain the printer ink parameters, including: the density, viscosity coefficient, and surface tension of the inkjet droplets;

[0010] (d) According to the printer ink parameters, compare with the scaling relation β of the maximum spreading diameter obtained from molecular dynamics simulationmax ~We 1 / 2 Re 1 / 5 and determine the most preferable parameters of the inkjet speed by simulating the impact effect of the snapshot; wherein, β max represents the normalized parameter of the maximum droplet impact maximum spreading factor; We represents the dimensionless parameter, which is the Weber number; Re represents the dimensionless parameter, which is the Reynolds number;

[0011] (e) Adjust the heating rate of the variable-speed heating device of the printer nozzle according to the most preferable parameters of the inkjet speed to improve the inkjet printing accuracy.

[0012] Furthermore, the inherent parameters of the printer inkjet nozzle include: nozzle inner diameter and inkjet speed.

[0013] Furthermore, the printer accuracy parameter is the highest resolution of the printer.

[0014] Furthermore, the step (d) includes:

[0015] According to the density ρ, viscosity coefficient μ and surface tension γ of the inkjet droplet, as known parameters; substitute into the formula: We = ρD0V0 2 / γ, Re = ρD0V0 / μ; V0 represents the impact speed of the droplet; D0 represents the droplet diameter, which is determined by the nozzle inner diameter;

[0016] And according to the scaling relation β max ~We 1 / 2 Re 1 / 5 , obtain the one-to-one correspondence between V0 and β max ;

[0017] Control β by controlling V0 max , and observe the relatively stable β max interval through molecular dynamics simulation, so as to obtain the most preferable parameter V0 of the inkjet speed.

[0018] Furthermore, β max represents the normalized parameter of the maximum droplet impact maximum spreading factor, and is obtained by the following formula:

[0019] β max = D max / D0

[0020] wherein, D max represents the droplet diameter at the maximum spreading moment.

[0021] In the second aspect, the present invention also provides a method for improving the inkjet printing accuracy based on molecular dynamics simulation, which changes the ink performance and optimizes the selection of the inkjet speed at the same time: the specific steps include:

[0022] (1) Determine the inherent parameters of the printer inkjet nozzle corresponding to the selected printer model;

[0023] (2) Calculate the diameter range of the printer ink droplets according to the corresponding printer precision parameters and inherent parameters;

[0024] (3) Obtain the printer ink parameters, including: the density, viscosity coefficient and surface tension of the ink droplets;

[0025] (4) According to the printer ink parameters, compare with the scaling relation β of the maximum spreading diameter obtained by molecular dynamics simulation max ~We 1 / 2 Re 1 / 5 and the impact effect of the simulation snapshot to determine the first most preferred parameter of the inkjet speed; where, β max represents the normalized parameter of the maximum droplet impact maximum spreading factor; We represents the dimensionless parameter, the Weber number; Re represents the dimensionless parameter, the Reynolds number;

[0026] (5) By adjusting the ink raw material ratio, change the density ρ' and viscosity coefficient μ' of the ink, and then calculate the surface tension γ' of the ink droplets. Re - conduct molecular dynamics simulation under the new parameters and conduct a stability analysis on the spreading dynamics of the ink droplets;

[0027] (6) Again, compare with the scaling relation β obtained by the simulation max ~We 1 / 2 Re 1 / 5 and the stability analysis results to re - determine the second most preferred parameter of the inkjet speed;

[0028] (7) According to the second most preferred parameter of the inkjet speed, adjust the heating rate of the variable - rate heating device of the printer nozzle to improve the inkjet printing precision.

[0029] Furthermore, the inherent parameters of the printer inkjet nozzle include: the nozzle inner diameter and the inkjet speed.

[0030] Furthermore, the printer precision parameter is the highest resolution of the printer.

[0031] Furthermore, step (4) includes:

[0032] According to the density ρ, viscosity coefficient μ and surface tension γ of the ink droplets, as known parameters; substitute into the formula: We = ρD0V0 2 / γ, Re = ρD0V0 / μ; V0 represents the impact speed of the droplet; D0 represents the droplet diameter, which is determined by the nozzle inner diameter;

[0033] And according to the scaling relation βmax ~We 1 / 2 Re 1 / 5 to obtain the one-to-one correspondence between V0 and β max ;

[0034] Control β by controlling V0 max , and observe the relatively stable β range of spreading through molecular dynamics simulation, so as to obtain the first most preferred parameter V0 of the inkjet speed. max

[0035]

[0036] max Furthermore, β represents the normalized parameter of the maximum droplet impact maximum spreading factor, and is obtained by the following formula:

[0037] β max = D max / D0

[0037] where D max represents the droplet diameter at the moment of maximum spreading.

[0038] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses and provides a method for improving the inkjet printing accuracy based on molecular dynamics simulation:

[0039] Solution 1: Without changing the nozzle parameters and ink properties, only optimizing the selection of the inkjet speed, the accurate control of the inkjet droplet speed can be achieved by adjusting the heating rate or the deformation rate of the micro piezoelectric ceramic. This method uses molecular dynamics simulation software to simulate and analyze the droplet impact and spreading dynamics at the microscale, and obtains the relationship between the droplet spreading characteristics and the inherent parameters of the droplet itself at the microscale level of the inkjet droplet scale or smaller, making up for the defect that data cannot be obtained through experiments at this scale, and significantly improving the printing accuracy.

[0040] Solution 2: Change the ink properties and optimize the selection of the inkjet speed at the same time. By changing the material or adjusting the ratio of the ink itself, change the ρ, γ, μ of the ink itself, and then combine the analysis of the stability of the spreading effect after simulation impact. According to the scaling relationship, calculate the best matching coefficient of the 4 parameters of ρ, γ, μ and V0, which can further improve the printing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0042] Figure 1 A flow chart of a method for improving inkjet printing accuracy based on molecular dynamics simulation according to Example 1 of the present invention;

[0043] Figure 2a Print software renderings in different sizes and multiple fonts for inkjet printers;

[0044] Figure 2b Printing renderings in different sizes and multiple fonts for inkjet printers;

[0045] Figure 3a Software renderings for printing regular graphics for inkjet printers;

[0046] Figure 3b Printing effect diagram of regular graphics printed by inkjet printer;

[0047] Figure 4a Original image when printing the same image in different sizes for inkjet printer;

[0048] Figure 4b Printing for inkjet printers Figure 4a Printing effect diagram of the picture;

[0049] Figure 5a - 5d Schematic diagram of the analysis of factors affecting the printing accuracy of inkjet printers, taking the Chinese character "口" as an example: (a) Schematic diagram of the effect of larger ink dot diameter before optimization, (b) Schematic diagram of the effect of reduced ink dot diameter after optimization, (c) Schematic diagram of the effect of poor inkjet stability before optimization, (d) Schematic diagram of the simulated printing effect at different sizes;

[0050] Figure 6a - 6c The following is an analysis diagram of inkjet droplet spreading stability based on MD simulation results. (a) Schematic diagram of the initial state of MD simulation, (b) the maximum spreading diameter β fitted by MD simulation results max Relationship diagram with We and Re, (c) MD simulation of the front view and top view of the maximum spreading moment of the droplet impacting the solid surface at different speeds. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] In the related art: The impact of a droplet on a solid surface is one of the most studied phenomena in surface science and has attracted great attention due to its importance in industrial applications, such as inkjet printing, spray cooling, wing anti-icing, surface self-cleaning, etc. After a droplet impacts a solid surface, different dynamic processes will occur, mainly manifested as spreading, retracting, depositing, splashing, and even rebounding on a superhydrophobic surface. All these remarkable phenomena are due to several competing forces involved in the impact process, including inertial force, capillary force, and viscous force. In addition, the physical properties (density, viscosity, surface tension, etc.) of the impacting droplet, together with the competing forces, determine the various outcomes of the impacting droplet.

[0053] To simplify the collision situation under study, several dimensionless parameters have been proposed to characterize the relationship between the competing forces and physical properties. These dimensionless parameters include the Weber number (We = ρD0V0 2 / γ) and the Reynolds number (Re = ρD0V0 / μ). The physical meaning of We is the ratio of inertial force to capillary force, and Re represents the ratio of inertial force to viscous force. Among them, ρ, γ, μ are the density, surface tension, and viscosity of the impacting droplet respectively; V0 and D0 are the impact velocity and diameter of the droplet respectively. Among various impact outcomes, the maximum spreading diameter is one of the most fundamental parameters and is directly related to practical applications.

[0054] For example, controlling the maximum wetting area of an impacting droplet on a solid surface is crucial for determining the resolution of an inkjet printer. The maximum spreading factor is usually normalized to β max = D max / D0, where D max is the diameter at the moment of maximum spreading. Since the capillary force in the viscous region can be ignored and the energy loss mainly comes from viscous dissipation, at any Weber number, the maximum spreading factor follows the scaling law of β max ~ Re 1 / 5 . On the other hand, the influence of viscous dissipation in the capillary region on β max can be basically ignored. Based on the force balance method, a prediction law for β max in the capillary region is proposed, expressed as β max ~ We 1 / 4 .

[0055] However, whether in practical applications or natural sciences, the impact system usually consists of multiple droplets (such as inkjet printing), which makes the impact process more complex. Through MD (molecular dynamics) simulation, the dynamic characteristics of the impact of binary nano-droplets on a solid surface are studied in a large Weber number range. The maximum spreading factor of the binary droplet system is mainly studied, and for β maxThe detailed relationship with We was compared and discussed. Different from the macroscale, water droplets at the nanoscale are highly sensitive to the intrinsic wettability (θ0), and we predicted that various different impact results would occur. Therefore, we constructed a relatively comprehensive phase diagram to present the influence of θ0 and We on its dynamic characteristics.

[0056] We found during the simulation process that the normalized spreading factor is insensitive to the intrinsic wettability at high We, indicating that β max can be predicted theoretically by the scaling law. First, we tried to use the recognized scaling relationship of β max ~We 1 / 4 to test whether this scaling law at the macroscale also applies to our micro-system. For this purpose, we plotted β of various θ0 max as a function of We 1 / 4 (13.6 to 255.29). The results show that the theoretical model underestimates β max , especially in the high We range. At the macroscale, the initial kinetic energy of the impacting droplet is not only converted into the surface energy stored during droplet deformation, but also forms a vortex motion at the droplet edge to store part of the energy in the form of internal kinetic energy. While at the nanoscale, the velocity gradient exists throughout the impacting droplet and the velocity boundary layer disappears. This indicates that the intense internal perturbation may disrupt the vortex motion inside the droplet as in the macroscale, thus reducing the energy consumption. Based on energy conservation, the impact kinetic energy is completely converted into surface energy, obtaining γ lv D 2 ~V 2 , so the maximum spreading factor can be derived as β max ~We 1 / 2 . Due to the non-negligible scale effect, the increasing viscous force at the nanoscale is also an important influencing factor in the current system, which destroys the kinetic energy in the form of viscous dissipation, with a scale of Re 1 / 5 . Therefore, we assume that β max should follow the combined law of We 1 / 2 and Re 1 / 5 , obtaining β max ~We 1 / 2 Re 1 / 5 . Then we plotted the data of β on the solid surface with different θ0 max versus We 1 / 2 Re 1 / 5 (13.6 < We < 255.29), indicating that the law of β max ~We 1 / 2 Re 1 / 5 is in good agreement with the MD data in the We range from 13.6 to 182.78.

[0057] Based on the above research on the characteristics of nano-droplet impinging on a solid surface and the obtained conclusions, it is very suitable for applying to the impact variation law of inkjet droplets in an inkjet printer. The size of the ink droplet can directly determine the width of the line on the substrate. A microelectronic printer is an inkjet process that forms lines by dots, and the diameter of the inner hole of the print head directly determines the controllable range of the ink droplet diameter, thus determining the resolution of inkjet printing. And for the control accuracy of inkjet droplets β max in inkjet printing technology, it basically determines the printing accuracy of a printer.

[0058] The method for improving inkjet printing accuracy based on molecular dynamics simulation provided by the embodiments of the present invention, from a brand-new perspective, on the basis that the resolution of the printer has been determined (the highest resolution of ordinary household or office black-and-white printers is 1200×1200, and the highest resolution of color printers is 4800×1200), based on the results of molecular dynamics simulation of nano-droplet impact, the scaling relationship between the maximum spreading diameter of nano-droplets impinging on a solid surface and We and Re is fitted, that is, β max ~We 1 / 2 Re 1 / 5 , We = ρD0V0 2 / γ, Re = ρD0V0 / μ, where ρ, γ, μ are the density, surface tension, and viscosity of the impacting droplet respectively; V0 and D0 are the impact velocity and diameter of the droplet respectively. D0 is determined by the inner diameter of the inkjet print head. According to the results of the simulation experiment, β max is jointly controlled by these 4 parameters of ρ, γ, μ, and V0.

[0059] Without changing the material of the ink itself, that is, ρ, γ, μ remain unchanged, combined with the analysis of the stability of the spreading effect after simulation impact, according to the scaling relationship, the most preferred range of V0 corresponding to the required β max can be calculated to obtain the V0 with the most stable spreading effect.

[0060] Specifically, according to β max ~We 1 / 2 Re 1 / 5 , We = ρD0V0 2 / γ, Re = ρD0V0 / μ, that is, β max ~(ρD0V0 2 / γ) 1 / 2 (ρD0V0 / μ) 1 / 5 , all parameters except V0 can be obtained by measurement, so as to obtain the one-to-one correspondence between V0 and β max , that is to say, β max can be controlled by controlling V0. Through MD simulation, a relatively stable β maxrange, thereby obtaining the V0 range that can ensure stable spreading, and effectively controlling β max stability, achieving the effect of improving printing accuracy.

[0061] If the material of the ink can be improved, by changing the material or adjusting the ratio of the ink itself, changing ρ, γ, μ of the ink itself, and then combining the analysis of the stability of the spreading effect after simulated impact, calculating the optimal matching coefficient combining the four parameters of ρ, γ, μ and V0 according to the scaling relationship, (for example, increasing the glue content of the ink, then ρ, γ, μ of the ink itself will all change, measuring the new parameter values, and then through β max ~We 1 / 2 Re 1 / 5 obtaining a new V0 range, and finally obtaining the optimal V0 range by repeatedly adjusting the ratio of various raw materials in the ink), then the printing accuracy can be further improved.

[0062] The purpose of the present invention is to provide a scientifically reasonable, more applicable and better effect inkjet printing accuracy improvement method based on molecular dynamics simulation, aiming to improve the inkjet printing accuracy from the perspectives of improving ink performance and inkjet speed, in view of the deficiencies of the existing technology.

[0063] Example 1:

[0064] Without changing the nozzle parameters and ink performance, only optimizing the selection of the inkjet speed: Referring to Figure 1 shown, the specific steps include:

[0065] (a) Select the printer model and determine the inherent parameters of the printer inkjet nozzle; among them, the inherent parameters of the nozzle are only the nozzle inner diameter and the inkjet speed, excluding the parameters of the ink;

[0066] (b) Calculate the diameter range of the printer inkjet droplets according to the printer accuracy parameters and the nozzle inner diameter parameters; among them, the printing resolution is a built-in parameter, which is the highest resolution of the printer, and the nozzle inner diameter can be obtained by measurement or based on the manufacturer's instructions.

[0067] (c) Calculate and measure the density, viscosity coefficient, and surface tension of the inkjet droplets according to the printer ink parameters; generally, these parameters need to be provided by the ink manufacturer or measured with measuring instruments. For example, the density can be calculated by mass / volume, and the viscosity coefficient and surface tension need to be obtained by measurement.

[0068] (d) Comparing with the scaling relation formula β of the maximum spreading diameter obtained by molecular dynamics simulation max ~We 1 / 2 Re 1 / 5And determine the most preferable range of the inkjet speed based on the impact effect of the simulated snapshots; specifically, on the one hand, the range of V0 corresponding to the desired range of β can be calculated through β max ~We 1 / 2 Re 1 / 5 On the other hand, the stability of spreading can be observed by referring to the simulation results. For example, max the first and second rows in Figure 6c show stable spreading, while the third row shows cracking phenomena at the edge and inside of the spreading droplet, which is unstable spreading. Finally, by combining the range of V0 calculated by us and the range of V0 obtained from the stability analysis, the final range of V0 to be selected is obtained, that is, the improved variable inkjet speed range.

[0069] Step d specifically includes the following:

[0070] d1), According to the density ρ, viscosity coefficient μ and surface tension γ of the inkjet droplet, as known parameters; substitute them into the formula: We = ρD0V0 2 / γ, Re = ρD0V0 / μ; V0 represents the impact speed of the droplet; D0 represents the droplet diameter, which is determined by the inner diameter of the nozzle;

[0071] d2), And according to the scaling relation β max ~We 1 / 2 Re 1 / 5 , obtain the one-to-one correspondence between V0 and β max ;

[0072] d3), Control β by controlling V0 max , and observe the relatively stable β max interval through molecular dynamics simulation, so as to obtain the most preferable parameter V0 of the inkjet speed.

[0073] Among them, β max represents the normalized parameter of the maximum droplet impact and the maximum spreading factor, and is obtained by the following formula:

[0074] β max = D max / D0

[0075] Among them, D max represents the droplet diameter at the moment of maximum spreading.

[0076] (e) According to the most preferable parameter of the inkjet speed, adjust the heating rate of the variable rate heating device of the printer nozzle to improve the inkjet printing accuracy.

[0077] For example, the fixed rate heating device of the inkjet printer nozzle part can be replaced with a variable rate heating device (or the fixed deformation rate of the micro piezoelectric ceramic can be changed to a variable deformation rate).

[0078] In this embodiment, on the basis of maintaining the original components of the inkjet printer, only the inkjet speed is optimized and adjusted. The fixed-inkjet-speed nozzle is replaced with a nozzle that can adjust the inkjet speed, and a technical effect of controllable inkjet droplet speed can be obtained by adjusting the heating rate or the deformation rate of the micro piezoelectric ceramic.

[0079] Embodiment 2:

[0080] Change the ink properties and optimize the selection of the inkjet speed at the same time:

[0081] (1) Determine the inherent parameters of the inkjet nozzle of the corresponding printer according to the selected printer model;

[0082] (2) Calculate the diameter range of the inkjet droplets of the printer according to the corresponding printer precision parameters and the inherent parameters;

[0083] (3) Obtain the printer ink parameters, including: the density, viscosity coefficient and surface tension of the inkjet droplets;

[0084] (4) According to the printer ink parameters, compare with the scaling relation β of the maximum spreading diameter obtained by molecular dynamics simulation max ~We 1 / 2 Re 1 / 5 and the impact effect of the simulation snapshot, determine the first most preferred selection parameter of the inkjet speed; where β max represents the normalized parameter of the maximum droplet impact maximum spreading factor; We represents the dimensionless parameter, which is the Weber number; Re represents the dimensionless parameter, which is the Reynolds number;

[0085] (5) By adjusting the ink raw material ratio, change the density ρ' and viscosity coefficient μ' of the ink, and then calculate the surface tension γ' of the inkjet droplets. Re-perform molecular dynamics simulation under the new parameters and conduct a stability analysis on the spreading dynamics of the ink droplets;

[0086] (6) Once again compare with the scaling relation β obtained by the simulation max ~We 1 / 2 Re 1 / 5 and the stability analysis results, and re-determine the second most preferred selection parameter of the inkjet speed;

[0087] (7) According to the second most preferred selection parameter of the inkjet speed, adjust the heating rate of the variable speed heating device of the printer nozzle to improve the inkjet printing accuracy.

[0088] Among them, steps (1)-(4) correspond to steps a-d of Embodiment 1 and are exactly the same. In this embodiment, only the inherent parameters of the inkjet nozzle are retained, that is, D0 is not changed. By changing the material of the ink itself or adjusting the ratio, ρ, γ, and μ of the ink itself are changed. Then, combined with the analysis of the stability of the spreading effect after simulated impact, according to the scaling relationship, the optimal matching coefficient combining these 4 parameters of ρ, γ, μ, and V0 is recalculated, which can further improve the printing accuracy.

[0089] Compared with the prior art, the method of the present invention is easy to implement. It is scientific, reasonable, and has strong applicability. By obtaining improved parameters through MD (molecular dynamics) simulation and stability analysis, the improvement effect of the printing accuracy is obvious.

[0090] The following further illustrates the above two embodiments with reference to the accompanying drawings:

[0091] Refer to Figure 2a - 2b As shown, it shows the printing effects of an inkjet printer printing Chinese characters in different font sizes and different fonts. Figure 2a The fonts shown are Song typeface, Boldface, Equal width, and Fangsong; the font sizes are Small Three, Four, Small Four, Six, Seven, and Eight, which are only for comparison and not fixed font and font size selections.

[0092] When the font size is relatively large, since the thickness of the strokes far exceeds the minimum accuracy of the printer, the printing effects are not very different. When the font size gradually decreases, the characteristics of different fonts gradually decrease. When the font size approaches the printing accuracy limit, it is almost difficult to distinguish the difference between fonts with the naked eye. In addition, when the strokes of various fonts of the same font size are uneven in thickness or have too many sharp corners (such as Figure 2a ), the printing effect is greatly affected by the printing accuracy. When the angle of the horizontal strokes in the strokes of the font is not horizontal (such as Figure 2a in the fourth column), the printing effect is more significantly affected by the accuracy. While fonts with relatively uniform stroke thickness or less angle change are less affected by the printing progress (such as Figure 2a in the second and third columns), especially when the font size is small.

[0093] Refer to Figure 3, Figure 3a - 3b It shows a comparison diagram of the effects of an inkjet printer printing straight lines with different widths. As the set line width continues to decrease, it is obvious that when the width setting reaches a certain limit, the thickness of the lines printed by the inkjet printer has no obvious difference, which means that the set width has reached the minimum limit width that this printer can print, so the printing accuracy is significantly affected. Figure 3b In the second column of , it shows the presentation methods of the printer at different depths. The depth is presented by the spraying density of ink dots. Smaller ink dot sizes mean that the printer can print more depth changes.Figure 3b The third column in

[0094] refers to Figure 4a - 4b and shows the comparison of the printing effects when the printer prints the same picture in different sizes. Obviously, more details are lost in the printed picture with a smaller size. For example, the pattern on the window is Figure 4b completely indistinguishable in

[0095] refers to Figure 5a - 5d As shown, taking the Chinese character "kou" as an example: (a) Schematic diagram of the effect of a larger ink dot diameter before optimization, (b) Schematic diagram of the effect of a reduced ink dot diameter after optimization, (c) Schematic diagram of poor inkjet stability before optimization, (d) Printing effect diagrams of the simulated printing effect in different sizes. On the premise of ensuring that the ink droplet impact reaches the critical liquid film thickness, appropriately reducing the inkjet speed can reduce the ink dot diameter. A smaller ink dot diameter directly affects the edge neatness of inkjet printing and the uniformity of the thickness of finer lines, thus directly affecting the printing accuracy. Secondly, the influence on the printing effect in terms of the uniformity or softness of the change in the black-and-white printing depth is also relatively obvious. In addition, for large-area solid black or darker printing, reducing the ink dot diameter can reduce the ink consumption and improve the printing speed.

[0096] refers to Figure 6a - 6c As shown, Figure 6b the scaling relationship β of the maximum spreading diameter of the droplet impacting the solid surface fitted through the MD simulation results max ~We 1 / 2 Re 1 / 5 shows the spreading laws of droplets on different hydrophilic and hydrophobic surfaces at different speeds. As Figure 6c shown, when the inkjet speed is small, the ink droplet fails to reach the critical liquid film thickness after impacting the solid surface, and the ink droplet may form a thicker ink layer or liquid beads on the surface, which will reduce the solidification speed of the ink and increase the ink consumption, so it does not meet the basic requirements of inkjet printing. When the speed is large, the ink droplet breaks or splashes after impact, greatly affecting the printing accuracy, so it does not meet the basic requirements of inkjet printing. MD simulation can analyze the impact process according to different droplet parameters (ρ, γ, μ) to obtain the stable spreading speed range, so adjusting the inkjet speed within the stable spreading speed range according to different printing requirements can effectively improve the printing accuracy.

[0097] According to the above theory and example analysis, the specific steps to improve the inkjet printing accuracy are as follows:

[0098] Step 1: Select the printer model and determine the inherent parameters of the printer's inkjet nozzles. Since the inner diameter of the inkjet nozzles directly determines the diameter of the inkjet droplets, without considering changing the size of the inkjet droplets (i.e., without changing the inherent resolution of the printer), the inkjet droplet diameter D0 is fixedly obtained and determined by the inner diameter of the nozzles.

[0099] Step 2: Calculate the range of the inkjet droplet diameter of the printer based on the printer's inherent parameters (inner diameter of the inkjet nozzles, inkjet speed) and the parameters of the control elements (heating rate, deformation rate); obtain parameters such as the density, viscosity coefficient, and surface tension of the ink.

[0100] Step 3: Determine the most preferred range of the inkjet speed according to the scaling relationship β of the maximum spreading diameter obtained from molecular dynamics simulation with We and Re max ~We 1 / 2 Re 1 / 5 (such as Figure 6b ) and the analysis of the spreading stability of the inkjet droplets based on the MD simulation results (such as Figure 6c ).

[0101] Step 4: Replace the inkjet speed control element of the printer, replace the fixed-rate heating device of the nozzle part of the inkjet printer with a variable-rate heating device (or change the fixed deformation rate of the micro piezoelectric ceramic to a variable deformation rate). According to the analysis of the impact on inkjet printing accuracy (such as Figure 5a - 5d ), the inkjet speed can be adjusted according to the printing requirements within the optimal inkjet speed range, thereby effectively improving the printing accuracy.

[0102] Step 5: By adjusting the ink raw material ratio, change the density and viscosity coefficient of the ink, and then calculate the surface tension of the inkjet droplets. Re-perform molecular dynamics simulation under the new parameters and conduct a stability analysis on the spreading dynamics of the ink droplets.

[0103] Step 6: Again, compare the obtained scaling relationship β max ~We 1 / 2 Re 1 / 5 and the stability analysis results, and re-determine the most preferred range of the inkjet speed, thereby further improving the printing accuracy.

[0104] The measuring instruments involved in the present invention are all commercially available products, and the simulation and analysis software are all obtained through open source.

[0105] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description in the method section.

[0106] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for improving the accuracy of inkjet printing based on molecular dynamics simulation, characterized in that, Without changing the nozzle parameters and ink properties, only optimize the selection of the inkjet speed. The specific steps include: (a) Determine the inherent parameters of the inkjet nozzle of the corresponding printer according to the selected printer model. The inherent parameters include: nozzle inner diameter and inkjet speed; (b) Calculate the diameter range of the inkjet droplets of the printer according to the corresponding printer precision parameters and the inherent parameters; (c) Obtain the printer ink parameters, including: density, viscosity coefficient and surface tension of the inkjet droplets; (d) Use molecular dynamics simulation software to simulate and analyze the droplet impact spreading dynamics at the microscale. According to the density ρ, viscosity coefficient μ, and surface tension γ of the inkjet droplet, which are known parameters, substitute them into the formulas: We = ρD0V0 2 / γ, Re = ρD0V0 / μ; V0 represents the impact velocity of the droplet; D0 represents the droplet diameter, which is determined by the inner diameter of the nozzle; Scaling relation β of the maximum spreading diameter obtained from the control molecular dynamics simulation max ~We 1 / 2 Re 1 / 5 And based on the impact effect of the simulation snapshots, the one-to-one correspondence between V0 and β max is obtained; Control β by controlling V0 max , and a relatively stable β of spreading is observed through molecular dynamics simulation max range, so as to obtain the most optimized parameter V0 for the inkjet speed; where β max represents the normalized parameter of the maximum droplet impacting the maximum spreading factor; We represents the dimensionless parameter, which is the Weber number; Re represents the dimensionless parameter, which is the Reynolds number (e) Adjust the heating rate of the variable-speed heating device of the printer nozzle according to the most preferred selection parameter of the inkjet speed to improve the inkjet printing precision.

2. The method for improving the inkjet printing accuracy based on molecular dynamics simulation according to claim 1, wherein The printer precision parameter is the highest resolution of the printer.

3. A method for improving the accuracy of inkjet printing based on molecular dynamics simulation according to claim 1, characterized in that, β max obtained by the following formula: β max = D max / D0 Among them, D max represents the droplet diameter at the maximum spreading moment.

4. A method for improving the accuracy of inkjet printing based on molecular dynamics simulation, characterized in that, Change the ink properties and optimize the selection of the inkjet speed at the same time: The specific steps include: (1) Determine the inherent parameters of the inkjet nozzle of the corresponding printer according to the selected printer model. The inherent parameters include: nozzle inner diameter and inkjet speed; (2) Calculate the diameter range of the inkjet droplets of the printer according to the corresponding printer precision parameters and the inherent parameters; (3) Obtain the printer ink parameters, including: density, viscosity coefficient and surface tension of the inkjet droplets; (4) Use molecular dynamics simulation software to simulate and analyze the droplet impact and spreading dynamics at the microscale. According to the density ρ, viscosity coefficient μ, and surface tension γ of the inkjet droplet, which are known parameters, substitute them into the formulas: We = ρD0V0 2 / γ, Re = ρD0V0 / μ; V0 represents the impact velocity of the droplet; D0 represents the droplet diameter, which is determined by the inner diameter of the nozzle; Scaling relation β of the maximum spreading diameter obtained from the comparative molecular dynamics simulation max ~We 1 / 2 Re 1 / 5 And based on the impact effect of the simulation snapshots, the one-to-one correspondence between V0 and β max is obtained; Control β by controlling V0 max , and a relatively stable spreading β is observed through molecular dynamics simulation max range, thereby obtaining the first most preferred parameter V0 of the inkjet speed; where β max represents the normalized parameter of the maximum droplet impact on the maximum spreading factor; We represents the dimensionless parameter, which is the Weber number; Re represents the dimensionless parameter, which is the Reynolds number; (5) By adjusting the ink raw material ratio, change the density ρ' and viscosity coefficient μ' of the ink, and then calculate the surface tension γ' of the inkjet droplets. Re-perform molecular dynamics simulation under the new parameters and conduct a stability analysis on the spreading dynamics of the ink droplets; (6) Recheck the scaling relation β obtained by simulation again max ~We 1 / 2 Re 1 / 5 and the results of stability analysis, and re-determine the second most preferred parameter for the inkjet speed; (7) Adjust the heating rate of the variable-speed heating device of the printer nozzle according to the second most preferred selection parameter of the inkjet speed to improve the inkjet printing precision.

5. A method for improving the inkjet printing accuracy based on molecular dynamics simulation according to claim 4, characterized in that The printer precision parameter is the highest resolution of the printer.

6. The method for improving the inkjet printing accuracy based on molecular dynamics simulation according to claim 5, wherein, β max obtained by the following formula: β max = D max / D0 Among them, D max represents the droplet diameter at the maximum spreading moment.

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