Design method of inkjet printing device and inkjet printing device

Abstract

The present disclosure relates to the field of inkjet printing, and specifically to a design method for an inkjet printing device and an inkjet printing device. The design method for an inkjet printing device includes: obtaining geometric parameters of a fluid calculation domain in the inkjet printing device and the spatial distribution of independent variable values ​​in the fluid calculation domain; establishing a dissipated work objective function according to the independent variables and establishing a topology optimization mathematical model according to the dissipated work objective function, and obtaining a topology optimization geometric model according to the geometric parameters and setting boundary conditions; obtaining the spatial distribution of design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model; obtaining a three-dimensional geometric design model according to the spatial distribution of design variable values ​​in the fluid calculation domain. Through the technical solution disclosed in the present disclosure, the influence of empirically designed geometric dimensions on flow channel performance is avoided, the subjective dependence of the design is eliminated, and the flow resistance of the fluid in the inkjet printing device is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of inkjet printing, and in particular to a design method for an inkjet printing device and an inkjet printing device. Background Art

[0002] With the development of micro-electromechanical technology and the improvement of inkjet printing requirements, the number of nozzles integrated in an inkjet head is increasing, and the corresponding microchannel density is getting higher and higher, which leads to smaller and smaller dimensions from the flow restriction to the pressure chamber and higher and higher flow resistance. The high flow resistance of the ink supply end flow channel will have a series of effects on the inkjet process. For example, the flow resistance in the direction of ink flowing from the pressure chamber to the nozzle increases, which will increase the pressure requirements provided by the piezoelectric film; the flow resistance of the flow restriction part where the ink flows from the common flow channel to the pressure chamber is too high, which will affect the ink filling process of the pressure chamber after inkjet, causing the nozzle to inhale air and affect the inkjet quality. Therefore, low-resistance ink supply flow channels and pressure chambers are the basis for ensuring the normal operation of inkjet heads, and are also an important way to improve their performance.

[0003] The pressure chamber is an important microfluidic device in the piezoelectric inkjet head. Due to the limitation of processing technology, the pressure chamber has a consistent structure in one direction in space, and the structure can be simplified into a two-dimensional graphic representation. Common pressure chambers include rectangular pressure chambers, circular pressure chambers, and diamond pressure chambers. The flow channel form of the pressure chamber is generally designed based on experience. However, this design method cannot fully consider the rationality of its shape, such as the flow dead zone problem inside the chamber, and the flow resistance problem of the complex flow channel layout. It is also unable to provide an efficient and reasonable appearance structure. Summary of the invention

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides a design method for an inkjet printing device and an inkjet printing device, which avoids the influence of empirically designed geometric dimensions on flow channel performance, eliminates the subjective dependence of the design, and reduces the flow resistance of the fluid in the inkjet printing device.

[0005] In a first aspect, the present disclosure provides a method for designing an inkjet printing device, comprising:

[0006] Acquire geometric parameters of a fluid computation domain in the inkjet printing device and independent variables in the fluid computation domain;

[0007] Establishing a dissipated work objective function according to the independent variables and establishing a topology optimization mathematical model according to the dissipated work objective function, and obtaining a topology optimization geometric model according to the geometric parameters and setting boundary conditions; obtaining the numerical spatial distribution of the design variables in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model;

[0008] The three-dimensional geometric design model is obtained according to the numerical spatial distribution of the design variables in the fluid calculation domain.

[0009] Optionally, the fluid calculation domain includes a design domain and a non-design domain, the design domain includes the restricting portion inlet and the pressure chamber, and the non-design domain includes the restricting portion straight channel and the pressure chamber outlet.

[0010] Optionally, the dissipated work objective function is:

[0011]

[0012] Wherein, Φ represents the dissipated work of fluid flow, γ is the design variable in the fluid calculation domain, used to characterize the presence or absence of solid material distribution in the design domain, η is the viscosity of the fluid, is the Hamiltonian operator, u is the flow velocity of the fluid, Ω is the fluid calculation domain,

[0013]

[0014] Among them, α min is the reverse osmosis rate of the fluid, α max is the reverse osmosis rate of the solid material, and q is the adjustment parameter of α(γ).

[0015] Optionally, the topology optimization mathematical model is:

[0016] Find

[0017] MinΦ

[0018]

[0019]

[0020] u=u0 onΓ in

[0021]

[0022]

[0023] 0≤γ≤1

[0024] Wherein, ρ is the density of the fluid, p is the pressure of the fluid, u0 is the velocity of the fluid at the inlet of the restricting portion, Γ in is the boundary of the inlet of the limiting part, Γ out is the boundary of the pressure chamber outlet, i is the i-th design domain, V i is the upper limit of the maximum volume of the fluid corresponding to the i-th design domain, and I is [1,1,1] T , n is the unit normal vector of the pressure chamber outlet boundary.

[0025] Optionally, set boundary conditions, including:

[0026] Acquire the boundary of the fluid calculation domain according to the geometric parameters;

[0027] Applying an inlet fluid velocity distribution boundary condition at the inlet boundary of the fluid calculation domain;

[0028] Applying an outlet boundary condition at the outlet boundary of the fluid computational domain;

[0029] A non-slip boundary condition is applied to the boundaries outside the fluid calculation domain inlet and the fluid calculation domain outlet.

[0030] Optionally, obtaining the spatial distribution of the numerical values ​​of the design variables in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model includes:

[0031] Meshing the topology optimized geometric model;

[0032] Get the maximum target calculation times and convergence accuracy;

[0033] Based on the topology optimization geometric model after mesh segmentation, an optimization algorithm is selected and the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized is obtained according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy.

[0034] Optionally, in the process of selecting an optimization algorithm based on the topology optimization geometric model after mesh segmentation and obtaining the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy, the method further includes:

[0035] A grayscale constraint condition is imposed on the design variables in the fluid calculation domain, and the grayscale constraint condition is:

[0036] ∫ Ω γ(1-γ)dΩ / ∫ Ω 1dΩ≤a

[0037] Wherein, γ is the design variable, Ω is the fluid calculation domain, and a is a real number much smaller than 0.25.

[0038] Optionally, obtaining the three-dimensional geometric design model according to the spatial distribution of the design variable values ​​of the fluid calculation domain includes:

[0039] The design variables in the fluid calculation domain are filtered, and the filtering satisfies the following calculation formula:

[0040]

[0041] Wherein, γ is the design variable, and b is a real number greater than 0.2 and less than 0.8;

[0042] The three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​after filtering.

[0043] Optionally, acquiring the three-dimensional geometric design model according to the spatial distribution of the design variable values ​​after filtering includes:

[0044] According to the spatial distribution of the design variable values ​​after filtering, interpolation fitting is performed on the contour of the spatial distribution of the design variable values ​​characterizing the absence of solid material to obtain the two-dimensional geometric contour;

[0045] The three-dimensional geometric design model is acquired according to the two-dimensional geometric outline.

[0046] In a second aspect, the present disclosure provides an inkjet printing device, which is designed and manufactured using the design method of the inkjet printing device according to the first aspect, and the inkjet printing device includes:

[0047] A liquid supply pool, a pressure chamber and a flow limiting portion, wherein the flow limiting portion includes a flow limiting portion inlet area and a flow limiting portion straight end, wherein the flow limiting portion inlet area is connected to the outlet of the liquid supply pool, and the outlet of the flow limiting portion straight area is connected to the inlet of the pressure chamber;

[0048] A drainage structure and a spraying structure, the outlet of the pressure chamber is connected to the inlet of the drainage structure, and the outlet of the drainage structure is connected to the spraying structure; wherein the outlet of the pressure chamber is the same in shape and size as the inlet of the drainage structure, and the outlet diameter of the drainage structure is larger than the diameter of the spraying structure.

[0049] Compared with the prior art, the technical solution provided by the present invention has the following advantages:

[0050] The geometric parameters of the fluid calculation domain in the inkjet printing device and the spatial distribution of the independent variable values ​​in the fluid calculation domain are obtained; the dissipated work objective function is established according to the independent variables and the topology optimization mathematical model is established according to the dissipated work objective function, and the topology optimization geometric model is obtained according to the geometric parameters and the boundary conditions are set; the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized is obtained according to the topology optimization mathematical model and the topology optimization geometric model; the three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​in the fluid calculation domain. Therefore, the embodiment of the present disclosure provides a method for designing an inkjet printing device using a topology optimization method, taking dissipated work as the objective function and constructing a topology optimization mathematical model, constructing a topology optimization geometric model according to the geometric parameters of the fluid calculation domain, obtaining the design variables of the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model, using the design variables to characterize the presence or absence of solid materials, and obtaining a three-dimensional geometric design model with low flow resistance according to the spatial distribution of the design variable values ​​in the fluid calculation domain. The topology optimization design method is automatically generated, avoiding the influence of the empirical design geometric dimensions on the flow channel performance, eliminating the subjective dependence of the design, and reducing the flow resistance of the fluid in the inkjet printing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of a flow chart of a design method of an inkjet printing device provided in an embodiment of the present disclosure;

[0052] Figure 2 A schematic diagram of the structure of a fluid calculation domain of an inkjet printing device provided in an embodiment of the present disclosure;

[0053] Figure 3 A two-dimensional geometric profile of an inkjet printing device provided in an embodiment of the present disclosure;

[0054] Figure 4 A three-dimensional geometric design model of an inkjet printing device provided in an embodiment of the present disclosure;

[0055] Figure 5 A schematic diagram of a specific flow chart of a design method for an inkjet printing device provided in an embodiment of the present disclosure;

[0056] Figure 6 A graph showing changes in the dissipated work objective function of an inkjet printing device design method according to an embodiment of the present disclosure as the optimization process progresses;

[0057] Figure 7 A schematic diagram of the structure of a design device for an inkjet printing device provided in an embodiment of the present disclosure;

[0058] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0060] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0061] Figure 1 The flowchart of a design method of an inkjet printing device provided by an embodiment of the present disclosure is shown. The design method of an inkjet printing device can be applied to the application scenario of designing an inkjet printing device, and can be executed by the design device of an inkjet printing device provided by an embodiment of the present disclosure. Figure 1 As shown, the design method of the inkjet printing device includes:

[0062] S101, obtaining geometric parameters of a fluid calculation domain in an inkjet printing device and spatial distribution of independent variable values ​​in the fluid calculation domain.

[0063] Figure 2 A schematic diagram of the structure of a fluid calculation domain in an inkjet printing device provided in an embodiment of the present disclosure, optionally, as Figure 2 As shown, the fluid calculation domain includes a design domain and a non-design domain. The design domain includes a flow restriction inlet 1 and a pressure chamber 3 , and the non-design domain includes a flow restriction straight channel 2 and a pressure chamber outlet 4 . Figure 2 It is exemplarily shown that the flow restriction inlet 1, the pressure chamber 3 and the flow restriction straight channel 2 are rectangular, and the pressure chamber outlet 4 is elliptical.

[0064] Specifically, Figure 2As shown, the flow restriction inlet 1 and the flow restriction straight channel 2 can be set to be connected, the flow restriction inlet 1 is used as the inlet of the fluid calculation domain of the inkjet printing device, the length and width of the flow restriction inlet 1 are set as the length of the design domain Ω1, L3, and the width is W3, the length and width of the pressure chamber 3 are used as the length of the design domain Ω2, L1, and the width is W1, the length and width of the flow restriction straight channel 2 are used as the length of the non-design domain, L2, and the width is W2, the flow restriction straight channel 2 is connected to the pressure chamber 3 and is set as the non-design domain, the outlet of the flow restriction straight channel 2 is used as the inlet of the pressure chamber 3, and the pressure chamber outlet 4 is used as the outlet of the fluid calculation domain, and the center of the pressure chamber outlet 4, that is, the distance from the ellipse center to the edge of the pressure chamber 3 is L4. When the ink needs to be ejected from the inkjet printing device, the ink enters from the flow restriction inlet 1 and is ejected from the pressure chamber outlet 4 along the direction X. It should be noted that the shape of the pressure chamber outlet 4 can be designed according to the outlet of the actual inkjet printing device, for example, it can be a circular, square or elliptical shape, etc., and the embodiment of the present disclosure is not limited to this.

[0065] After determining the geometric parameters of the fluid calculation domain in the inkjet printing device, including the length L3 and width W3 of the design domain Ω1, the length L1 and width W1 of the design domain Ω2, and the length L2 and width W2 of the non-design domain, the spatial distribution of the independent variable values ​​of the limiting portion inlet 1 in the fluid calculation domain is determined according to parameters such as the inkjet frequency of the inkjet printing device during actual printing, the properties of the ink used, and the size of a single ink droplet. The independent variables of the limiting portion inlet 1 include the ink flow velocity u, the ink density ρ, and the ink viscosity η at the limiting portion inlet 1. The independent variables of the limiting portion inlet 1 do not change with the changes of the inkjet printing device during the topology optimization design process, but are determined by the properties of the inkjet printing device itself and the ink used.

[0066] S102, establishing a dissipated work objective function according to independent variables and establishing a topology optimization mathematical model according to the dissipated work objective function, and obtaining a topology optimization geometric model according to geometric parameters and setting boundary conditions.

[0067] Specifically, in order to ensure that the pressure chamber 3 is convenient for the ejection and filling of the fluid, the pressure loss should be minimized during the fluid flow process, and the flow resistance should be as small as possible. Therefore, the dissipated work of the fluid flow is established as the objective function based on the independent variable to avoid the problem of flow dead zone in the designed inkjet printing device and reduce the resistance of the fluid flow. By introducing the dissipated work as the objective function in the topology optimization mathematical model, the constraint conditions are used to minimize the value of the objective function, that is, the fluid flow resistance is minimized, and then the spatial distribution of the design variable γ value corresponding to the minimum objective function is found. At the same time, the topology optimization geometric model can be designed according to the length L3 and width W3 of the design domain Ω1 of the fluid calculation domain in the inkjet printing device, the length L1 and width W1 of the design domain Ω2, and the length L2 and width W2 of the non-design domain, and the boundary conditions are used to restrict the topology optimization geometric model.

[0068] Optionally, the dissipated work objective function is:

[0069]

[0070] Where Φ represents the dissipated work of fluid flow, γ is the design variable of the fluid computational domain, η is the viscosity of the fluid, is the Hamiltonian operator, u is the flow velocity of the fluid, Ω is the fluid calculation domain,

[0071]

[0072] Among them, α min is the reverse osmosis rate of the fluid, α max is the reverse osmosis rate of the solid material, and q is the adjustment parameter of α(γ).

[0073] Specifically, the dissipated work objective function is an integral function of the design variables in the fluid calculation domain, and the design variable γ is a variable in the dissipated work objective function. When the dissipated work reaches the minimum value, the spatial distribution of the value of the design variable γ can be obtained. When the dissipated work of fluid flow is used as the objective function, the dissipated work Φ corresponds to the spatial distribution of the value of the design variable γ one by one. The spatial distribution of the value of the design variable γ is used to characterize the presence or absence of solid materials at the corresponding positions of the design domain Ω1 and the design domain Ω2. α is a function of the design variable γ. In the formula α(γ), q is a positive real number used to adjust the concavity of the α(γ) curve. α min For example, it can be set to 0, which means the reverse osmosis rate of the fluid is the smallest and the fluid flow resistance is the smallest. max For example, it can be as large as possible. The greater the reverse osmosis rate of the fluid, the greater the fluid flow resistance. max The value of can change with the topology optimization process, or it can be a fixed value that does not change with the topology optimization process. maxWhen the value is too large, numerical instability is likely to occur. In the embodiment of the present disclosure, α(γ) is taken to be large enough but finite to ensure the numerical stability of the optimization problem and to be close to the actual situation. In addition, the formula for the dissipated work of fluid flow is well known to those skilled in the art and will not be discussed in detail here.

[0074] Optionally, the topology optimization mathematical model is:

[0075] Findγ (1)

[0076] MinΦ (2)

[0077]

[0078]

[0079] u=u0 onΓ in (5)

[0080]

[0081]

[0082] 0≤γ≤1 (8)

[0083] Where, ρ is the density of the fluid, p is the pressure of the fluid, u0 is the velocity of the fluid at the inlet 1 of the restriction, Γ in is the boundary of the restricting part inlet 1, Γ out is the boundary of the pressure chamber outlet 4, i is the i-th design domain, V i is the upper limit of the maximum volume of the fluid corresponding to the i-th design domain, I is [1,1,1] T , n is the unit normal vector of the outlet boundary.

[0084] Specifically, commonly used topology optimization mathematical models are usually composed of design variables, objective functions and constraints. The specific principles are well known to those skilled in the art and will not be elaborated here. The embodiment of the present disclosure considers the Navier-Stokes equations and their constraints that describe the fluid motion state to establish a topology optimization mathematical model. In the topology optimization mathematical model, formula (2) is used to solve the minimum value of the objective function, and the value of the design variable in formula (1) corresponding to the minimum objective function is found. Formula (3) is used to set the divergence of the velocity in the fluid calculation domain to 0 to represent that the fluid is incompressible, formula (4) is used to represent the force balance of the fluid, formula (5) is used as the boundary condition of the fluid flow rate at the inlet of the fluid calculation domain, i.e., the inlet 1 of the flow limiting part, formula (6) is used as the boundary condition of the fluid flow rate at the outlet of the fluid calculation domain, i.e., the outlet 4 of the pressure chamber, and formula (7) is used as the volume constraint of the topology optimization mathematical model to limit the maximum volume upper limit of the fluid corresponding to the i design domains. Figure 2In the example, two design domains are set. Different numbers of design domains can be set according to different design objects in the topology optimization process, and the embodiments of the present disclosure do not limit this. Formula (8) limits the design variable γ obtained in the mathematical model of topology optimization to a real number between 0 and 1. The design variable γ of 0 corresponds to solid materials, and the design variable γ of 1 corresponds to liquid materials. Therefore, by introducing dissipated work as the objective function in the mathematical model of topology optimization, the constraint condition is used to minimize the value of the objective function, that is, minimize the fluid flow resistance, and then find the spatial distribution of the value of the design variable γ corresponding to the minimum objective function.

[0085] Optionally, setting boundary conditions includes: obtaining the boundary of the fluid calculation domain according to geometric parameters; applying inlet fluid velocity distribution boundary conditions at the inlet boundary of the fluid calculation domain; applying outlet boundary conditions at the outlet boundary of the fluid calculation domain; and applying non-slip boundary conditions at the boundaries outside the inlet and outlet of the fluid calculation domain.

[0086] Specifically, Figure 2 As shown, the design domain Ω1, i.e., the pressure chamber 3, and the design domain Ω2, i.e., the flow restriction inlet 1 and the flow restriction straight 2 in the topology optimization geometric model are rectangular. The flow restriction inlet 1 and the pressure chamber outlet 4 are respectively applied with the boundary conditions u0 of the fluid velocity distribution at the flow restriction inlet 1 and the pressure chamber outlet 4. The width of the flow restriction inlet 1 is W3, and the width of the pressure chamber outlet 4 is W1. Non-slip boundary conditions are applied at the boundaries outside the flow restriction inlet 1 and the pressure chamber outlet 4, i.e., outside the fluid calculation domain inlet and outlet. The non-slip boundary conditions are that the velocity of the fluid is 0.

[0087] A limited flow straight channel 2 is set between the pressure chamber 3 and the limited flow inlet 1, and the limited flow straight channel 2 is set as a non-design domain. Since the length of the limited flow straight channel 2 does not affect the generation of the structures in the two design domains, in order to save computing resources during the topology optimization calculation process, the length of the limited flow straight channel 2 in the topology optimization geometric model can be set to be smaller than the actual length of the limited flow straight channel 2. In addition, if the shape in the topology optimization geometric model is symmetrical, for example, Figure 2 For the up-and-down symmetrical structure shown in the figure, or the left-and-right symmetrical structure, symmetrical boundary conditions can be applied on the symmetry axis, so that only half of the fluid calculation domain is analyzed to save computing resources.

[0088] S103. Obtain the spatial distribution of the numerical values ​​of the design variables in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model.

[0089] Optionally, the spatial distribution of the values ​​of the design variables in the fluid calculation domain when the dissipated work objective function is minimized is obtained based on the topology optimization mathematical model and the topology optimization geometric model, including: meshing the topology optimization geometric model; obtaining the maximum target calculation times and convergence accuracy; based on the topology optimization geometric model after meshing, selecting an optimization algorithm and obtaining the spatial distribution of the values ​​of the design variables in the fluid calculation domain when the dissipated work objective function is minimized based on the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy.

[0090] Specifically, the topology optimization geometric model is meshed, for example, quadrilateral meshing or triangular meshing can be used. The flow channel boundary position is also meshed during the topology optimization process. There are multiple mesh nodes in the meshed topology optimization geometric model. One mesh node corresponds to one design variable. The design variable value of the mesh node is solved. According to the solid material or liquid material corresponding to the design variable value, the distribution of the fluid flow channel in the design domain Ω1 and the design domain Ω2 can be obtained. After the topology optimization mathematical model is established, when the Navier-Stokes equation is solved to obtain the minimum value of the objective function, the sensitivity, that is, the gradient of the objective function with respect to the design variable, is solved at the same time. The accuracy of the sensitivity solution directly affects the convergence of the result. The sensitivity can be calculated using the adjoint equation derived from the topology optimization mathematical model. Optimization by solving the sensitivity belongs to the gradient optimization method. When there are many design variables, the gradient optimization method has much less calculation amount than the non-gradient optimization method, and it is easier to find the optimal solution.

[0091] In addition, it is necessary to use a suitable optimization algorithm for numerical optimization. The essence of numerical optimization is to find the minimum value of the objective function under certain constraints until the stopping criterion is met. The stopping criterion can be set to the number of calculations or the convergence accuracy. The optimization algorithm can be, for example, a nonlinear sequence quadratic programming algorithm or a moving asymptotic algorithm MMA (The Method of Moving Asymptotes). The embodiment of the present disclosure selects the moving asymptotic algorithm MMA suitable for processing multiple constraints as the optimization algorithm to iteratively optimize and update the distribution of design variables, set the maximum target number of calculations to 200 times, and set the convergence accuracy to 1E -6 , and finally get the optimization result, so that the material distribution in the design domain is reasonable. After the optimization algorithm calculation, according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy, the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized can be obtained, and the topology optimization design of the inkjet printing device can be carried out.

[0092] Optionally, in the process of selecting an optimization algorithm based on the topology optimization geometric model after mesh segmentation and obtaining the spatial distribution of the numerical values ​​of the design variables in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy, it also includes: applying grayscale constraints to the design variables in the fluid calculation domain, and the grayscale constraints are:

[0093] ∫ Ω γ(1-γ)dΩ / ∫ Ω 1dΩ≤a

[0094] Among them, γ is the design variable, Ω is the fluid calculation domain, and a is a real number less than 0.25.

[0095] Specifically, in order to make the binarization of the design variables more obvious, grayscale constraints can be imposed on the design variables in the fluid calculation domain during the topology optimization process to ensure that the calculation results of the design variables are closer to 0 or 1, and then correspond to the presence or absence of solid materials, so that the flow channel boundary of the fluid is clearer. The real number a can be selected as any real number much smaller than 0.25. The embodiment of the present disclosure exemplarily selects the real number a as 0.01. The user can choose whether to apply grayscale constraints and the value of the selected real number a according to the actual topology optimization design. The embodiment of the present disclosure does not limit this. The grayscale constraints imposed on the optimization algorithm are well known to those skilled in the art and will not be discussed in detail here.

[0096] S104. Obtain a three-dimensional geometric design model according to the spatial distribution of the design variable values ​​in the fluid calculation domain.

[0097] Optionally, obtaining a three-dimensional geometric design model according to design variables in the fluid calculation domain includes: performing filtering processing on the design variables in the fluid calculation domain, wherein the filtering processing satisfies the following calculation formula:

[0098]

[0099] Where, γ is the design variable, b is a real number greater than 0.2 and less than 0.8;

[0100] A three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​after filtering.

[0101] Specifically, after solving the design variables in the fluid calculation domain when the dissipated work objective function is minimized, in order to ensure that the obtained image can present an obvious black and white effect, the design variables need to be filtered so that the numerical values ​​of the design variables greater than or equal to the set real number b are all 1, and the numerical values ​​of the design variables less than the set real number b are all 0. In the embodiment of the present disclosure, the value of the real number b can be selected as 0.55, that is, the numerical values ​​of the design variables greater than or equal to 0.55 are all 1, and the numerical values ​​of the design variables less than 0.55 are all 0. The design variable value of 1 corresponds to the liquid phase material, that is, the flow channel, and the design variable value of 0 corresponds to the solid material, thereby making the two-dimensional geometric contour of the fluid calculation domain clearer and solving the grayscale problem of the boundary during the topology optimization process.

[0102] Optionally, a three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​after filtering, including: interpolating and fitting the contour of the spatial distribution of the design variable values ​​characterizing the solid material-free according to the spatial distribution of the design variable values ​​after filtering to obtain a two-dimensional geometric contour; and obtaining the three-dimensional geometric design model according to the two-dimensional geometric contour.

[0103] Figure 3 A two-dimensional geometric profile of an inkjet printing device is provided in an embodiment of the present disclosure. Specifically, the design variable after filtering takes the value of 0 or 1, and the spatial distribution information of the design variable value is imported into three-dimensional simulation software or three-dimensional design software. The spatial distribution of the design variable value characterizing the absence of solid material, that is, the regional profile where the design variable is 1, is interpolated and fitted with a B-spline curve to obtain a smooth two-dimensional geometric profile. Figure 3 The black area in the middle is the solid material part corresponding to the design variable value of 0. In order to facilitate display, the gray area is set as the part without solid material corresponding to the design variable value of 1. The black solid line in the gray area is the streamline of liquid flow. The two-dimensional geometric outline of the fluid calculation domain is obtained based on the intersection of the black area and the gray area.

[0104] Figure 4 A three-dimensional geometric design model of an inkjet printing device provided in an embodiment of the present disclosure is established according to the height longitudinal stretching of the two-dimensional geometric contour of the inkjet printing device actually used. Figure 4 The three-dimensional geometric design model shown in FIG. 3 includes the flow restriction inlet 1, the flow restriction 2 straight channel, the pressure chamber 3, the pressure chamber outlet 4, the liquid supply pool 5, the drainage structure 6 and the ejection structure 7 of the inkjet printing device, wherein the liquid supply pool 5, the drainage structure 6 and the ejection structure 7 are non-fluid calculation domains in the topology optimization design method. Therefore, the inkjet printing device designed using the topology optimization design method can reduce the flow resistance of the fluid and reasonably avoid the flow dead zone.

[0105] It should be noted that the software for designing the three-dimensional geometric model of the inkjet printing device can select CAD (Computer Aided Design) or CAE (Computer Aided Engineering) and other software to design the three-dimensional geometric model, and the embodiments of the present disclosure are not limited to this.

[0106] Figure 5 The following is a schematic diagram of a specific process of designing a method for an inkjet printing device provided by an embodiment of the present disclosure. Figure 5 As shown, the design method of the inkjet printing device includes:

[0107] S501. Start.

[0108] S502, obtaining geometric parameters of the fluid calculation domain in the inkjet printing device and the spatial distribution of the values ​​of independent variables in the fluid calculation domain.

[0109] S503. Establish a topology optimization mathematical model and a topology optimization geometric model.

[0110] S504, solving the Navier-Stokes equation in the topology optimization mathematical model to obtain the objective function value.

[0111] S505, solving the adjoint equation and calculating the sensitivity distribution.

[0112] S506. Use an optimization algorithm to update the design variable distribution of the fluid calculation domain.

[0113] S507: Whether to apply grayscale constraints on design variables in the fluid calculation domain. If so, execute step 508; if not, execute step 509.

[0114] S508. Apply grayscale constraints on design variables in the fluid calculation domain.

[0115] S509 , determine whether the objective function converges, if so, execute step 510 ; if not, execute step 504 .

[0116] S510, obtaining a two-dimensional geometric profile according to the spatial distribution of the design variable values ​​after filtering.

[0117] S511. Acquire a three-dimensional geometric design model according to the two-dimensional geometric outline and the design height of the inkjet printing device.

[0118] S512, end.

[0119] The advantages of the embodiments of the present disclosure can be further illustrated by the following simulation examples:

[0120] The length L1 of the design domain Ω1, i.e., the pressure chamber 3, is set to 450 microns, the width W1 is set to 300 microns, the length L2 of the flow restriction straight channel 2 is set to 100 microns, the width W2 is set to 30 microns, the length L3 of the flow restriction inlet 1, i.e., the width W3 is set to 200 microns, the distance L4 from the center of the pressure chamber outlet 4 to the edge of the pressure chamber 3 is set to 100 microns, and the shape of the pressure chamber outlet 4 is set to be as follows: Figure 2 The ellipse shown has a major semi-axis of 100 microns and a minor semi-axis of 50 microns. The left side of the inlet 1 of the flow restriction section in the fluid calculation domain is the inlet corresponding to formula (5) as the velocity distribution boundary condition at the inlet of the fluid calculation domain. The velocity distribution is parabolic, and the Reynolds number is selected as 3. The pressure chamber outlet 4 is the outlet of the fluid calculation domain corresponding to formula (6) as the velocity distribution boundary condition at the outlet of the fluid calculation domain. Non-slip boundary conditions are applied to the other boundaries, and the boundary condition is that the fluid velocity is 0.

[0121] By using the design method of the inkjet printing device provided in the embodiment of the present disclosure, the pressure chamber 3 and the flow limiting part 2 are optimized for flow channel topology design, and the following is obtained: Figure 3 The two-dimensional geometric outline is shown. The black solid line represents the streamline of the fluid. The streamline distribution shows that the topology optimized flow channel reasonably avoids the appearance of flow dead zone. Figure 6 A graph showing the change of the dissipated work objective function of the design method of an inkjet printing device provided by an embodiment of the present disclosure along with the optimization process, Figure 6 The horizontal axis represents the target calculation times, and the vertical axis represents the normalized value of the dissipated work objective function, such as Figure 6 As shown in the figure, the dissipated work objective function value first decreases and then converges to the same value during the iterative calculation process, indicating that the flow resistance of the design structure is extremely small. Finally, the following is obtained: Figure 4 The three-dimensional geometric design model of the inkjet printing device is established using the topology optimization design results.

[0122] The embodiment of the present disclosure provides a method for designing an inkjet printing device using a topology optimization method, taking dissipated work as an objective function and constructing a topology optimization mathematical model, constructing a topology optimization geometric model according to geometric parameters of a fluid calculation domain, obtaining the spatial distribution of the values ​​of design variables in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model, using design variables to characterize the presence or absence of solid materials, and obtaining a three-dimensional geometric design model with low flow resistance according to the spatial distribution of the values ​​of design variables in the fluid calculation domain. The topology optimization design method is automatically generated, avoiding the influence of empirical design geometric dimensions on flow channel performance and eliminating subjective dependence on the design. At the same time, mature gradient optimization methods such as the moving asymptotic method are used to solve the optimization problem, and the optimization convergence process is stable.

[0123] The disclosed embodiment also provides a design device for an inkjet printing device. Figure 7The schematic diagram of the structure of a design device for an inkjet printing device provided by an embodiment of the present disclosure. Figure 7 As shown, the design device of the inkjet printing device includes a geometric parameter and independent variable acquisition module 701, a topology optimization model building module 702, a design variable acquisition module 703 and a three-dimensional geometric design model acquisition module 704. The geometric parameter and independent variable acquisition module 701 is used to obtain the geometric parameters of the fluid calculation domain in the inkjet printing device and the independent variables in the fluid calculation domain, the topology optimization model building module 702 is used to establish the dissipated work objective function according to the independent variables and establish the topology optimization mathematical model according to the dissipated work objective function, and to obtain the topology optimization geometric model and its boundary conditions according to the geometric parameters, the design variable acquisition module 703 is used to obtain the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model, and the three-dimensional geometric design model acquisition module 704 is used to obtain the three-dimensional geometric design model according to the spatial distribution of the design variable values ​​in the fluid calculation domain.

[0124] The present disclosure also provides an electronic device, Figure 8 The structure diagram of an electronic device provided by the embodiment of the present disclosure is shown in FIG. Figure 8 As shown, the electronic device includes a processor and a memory. The processor executes the steps of the design method of the inkjet printing device in the above embodiment by calling the program or instructions stored in the memory. Therefore, it has the beneficial effects of the above embodiment and will not be repeated here.

[0125] like Figure 8 As shown, the electronic device may include at least one processor 801, at least one memory 802, and at least one communication interface 803. The components in the electronic device are coupled together via a bus system 804. The communication interface 803 is used to transmit information with external devices. It is understood that the bus system 804 is used to achieve connection and communication between these components. In addition to the data bus, the bus system 804 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, the bus system 804 is not described in detail. Figure 8 Various buses are labeled as bus system 804 .

[0126] It is understood that the memory 802 in this embodiment may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. In some implementations, the memory 802 stores the following elements: executable units or data structures, or their subsets, or their extended sets of operating systems and applications. In the embodiment of the present disclosure, the processor 801 executes the steps of each embodiment of the design method of the inkjet printing device provided in the embodiment of the present disclosure by calling the program or instruction stored in the memory 802.

[0127] The design method of the inkjet printing device provided in the embodiment of the present disclosure can be applied to the processor 801, or implemented by the processor 801. The processor 801 can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit in the processor 801 or the instruction in the form of software. The above-mentioned processor 801 can be a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0128] The steps of the design method of the inkjet printing device provided by the embodiment of the present disclosure can be directly embodied as being executed by a hardware decoding processor, or being executed by a combination of hardware and software units in the decoding processor. The software unit can be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 802, and the processor 801 reads the information in the memory 802 and completes the steps of the method in combination with its hardware.

[0129] The electronic device may also include one physical component, or multiple physical components, according to the instructions generated by the processor 801 when executing the design method of the inkjet printing device provided in the embodiment of the present application. Different physical components can be set inside the electronic device, or outside the electronic device, such as a cloud server, etc. Each physical component cooperates with the processor 801 and the memory 802 to realize the functions of the electronic device in this embodiment.

[0130] The present disclosure also provides a storage medium, such as a computer-readable storage medium, which stores a program or instruction. The program or instruction enables a computer to execute a method for designing an inkjet printing device, the method comprising:

[0131] Obtaining geometric parameters of a fluid computation domain in an inkjet printing device and spatial distribution of independent variable values ​​in the fluid computation domain;

[0132] Establishing a dissipated work objective function according to independent variables and establishing a topology optimization mathematical model according to the dissipated work objective function, and obtaining a topology optimization geometric model according to geometric parameters and setting boundary conditions;

[0133] According to the topology optimization mathematical model and the topology optimization geometric model, the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized is obtained;

[0134] The three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​in the fluid calculation domain.

[0135] Optionally, when executed by a computer processor, the computer executable instructions may also be used to execute the technical solution of the method for designing an inkjet printing device provided in any embodiment of the present disclosure.

[0136] Through the above description of the implementation method, the technicians in the relevant field can clearly understand that the present application can be implemented with the help of software and necessary general hardware, and of course it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application can be essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various embodiments of the present disclosure.

[0137] The present disclosure also provides an inkjet printing device, which is designed using the inkjet printing device design method as described above. Figure 4 As shown, the inkjet printing device includes a liquid supply pool 5, a pressure chamber 3 and a flow limiting portion 2, the flow limiting portion 2 includes a flow limiting portion inlet 1 area and a flow limiting portion straight channel 2 end, the flow limiting portion inlet 1 area is connected to the outlet of the liquid supply pool 5, and the outlet of the flow limiting portion straight channel 2 area is connected to the inlet of the pressure chamber 3; a drainage structure 6 and a spraying structure 7, the pressure chamber outlet 4 is connected to the inlet of the drainage structure 6, and the outlet of the drainage structure 6 is connected to the spraying structure 7; wherein the pressure chamber outlet 4 is the same shape and size as the inlet of the drainage structure 6, and the outlet diameter of the drainage structure 6 is larger than the diameter of the spraying structure 7.

[0138] Specifically, Figure 4As shown, the ink in the inkjet printing device is stored in the liquid supply pool 5. When the inkjet printing device needs to eject ink, the ink enters the end of the straight channel 2 of the flow restriction portion through the inlet 1 area of ​​the flow restriction portion from the liquid supply pool 5. The end of the straight channel 2 of the flow restriction portion can reduce the backflow of the ink in the pressure chamber 3, reduce the pressure loss in the pressure chamber 3, and improve the ejection performance of the inkjet printing device. A drainage structure 6 is arranged between the pressure chamber 3 and the ejection structure 7. The inlet of the drainage structure 6 and the outlet 4 of the pressure chamber are completely the same in shape and size. The ink flows into the drainage structure 6 from the outlet 4 of the pressure chamber. Adding the drainage structure 6 is conducive to reducing the local pressure loss caused by the sudden change of the cross section from the pressure chamber 3 to the ejection structure 7, and at the same time reducing the pressure loss in the pressure chamber 3 caused by the deformation of the ejection structure 7. The ejection structure 7 is used to eject the ink. The diameter of the ejection structure 7 is smaller than the outlet of the drainage structure 6. For example, a nozzle in a conical or funnel shape can be selected as the ejection structure 7 to avoid the interruption of printing caused by bubbles generated at the nozzle, reduce the flow resistance of the ink, and facilitate the ejection of the ink.

[0139] Therefore, the pressure chamber and the transition flow channel at the inlet of the flow limiting part in the inkjet printing device designed by the topology optimization method in the embodiment of the present disclosure have low flow resistance, avoiding the dead zone problem inside the chamber and improving the ejection speed of liquids such as ink.

[0140] It should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0141] The above are only specific embodiments of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for designing an inkjet printing device, characterized in that: include: Acquire geometric parameters of a fluid calculation domain in the inkjet printing device and spatial distribution of independent variable values ​​in the fluid calculation domain; Establishing a dissipated work objective function according to the independent variable values ​​and establishing a topology optimization mathematical model according to the dissipated work objective function, and acquiring a topology optimization geometric model according to the geometric parameters and setting boundary conditions; Obtaining the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimum according to the topology optimization mathematical model and the topology optimization geometric model; Acquire a three-dimensional geometric design model according to the spatial distribution of the design variable values ​​in the fluid calculation domain; Wherein, the fluid calculation domain includes a design domain and a non-design domain, the design domain includes a flow restriction inlet and a pressure chamber, and the non-design domain includes a flow restriction straight channel and a pressure chamber outlet; The dissipated work objective function is: Wherein, Φ represents the dissipated work of fluid flow, γ is the design variable in the fluid calculation domain, which is used to characterize the presence or absence of solid material distribution in the design domain, η is the viscosity of the fluid, ▽ is the Hamiltonian operator, u is the flow velocity of the fluid, Ω is the fluid calculation domain, Among them, α min is the reverse osmosis rate of the fluid, α max is the reverse osmosis rate of the solid material, q is the adjustment parameter of α(γ); The topology optimization mathematical model is: Find MinΦ u=u0 onΓ in 0≤γ≤1 Wherein, ρ is the density of the fluid, p is the pressure of the fluid, u0 is the velocity of the fluid at the inlet of the restricting portion, Γ in is the boundary of the inlet of the limiting part, Γ out is the boundary of the pressure chamber outlet, i is the i-th design domain, V i is the upper limit of the maximum volume of the fluid corresponding to the i-th design domain, and I is [1,1,1] T , n is the unit normal vector of the pressure chamber outlet boundary.

2. The design method of an inkjet printing device according to claim 1, characterized in that: Setting boundary conditions includes: Acquire the boundary of the fluid calculation domain according to the geometric parameters; Applying an inlet fluid velocity distribution boundary condition at the inlet boundary of the fluid calculation domain; Applying an outlet boundary condition at the outlet boundary of the fluid computational domain; A non-slip boundary condition is applied to the boundaries outside the fluid calculation domain inlet and the fluid calculation domain outlet.

3. The design method of an inkjet printing device according to claim 1, characterized in that: Obtaining the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model and the topology optimization geometric model, including: Meshing the topology optimized geometric model; Get the maximum target calculation times and convergence accuracy; Based on the topology optimization geometric model after mesh segmentation, an optimization algorithm is selected and the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized is obtained according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy.

4. The method for designing an inkjet printing device according to claim 3, characterized in that: In the process of selecting an optimization algorithm based on the topology optimization geometric model after mesh segmentation and obtaining the spatial distribution of the design variable values ​​in the fluid calculation domain when the dissipated work objective function is minimized according to the topology optimization mathematical model, the maximum target calculation times and the convergence accuracy, the method further includes: A grayscale constraint condition is imposed on the design variables in the fluid calculation domain, and the grayscale constraint condition is: ∫ Ω γ(1-γ)dΩ / ∫ Ω 1dΩ≤a Wherein, γ is the design variable, Ω is the fluid calculation domain, and a is a real number less than 0.

25.

5. The method for designing an inkjet printing device according to claim 1, characterized in that: Acquiring a three-dimensional geometric design model according to the design variables in the fluid calculation domain includes: The design variables in the fluid calculation domain are filtered, and the filtering satisfies the following calculation formula: Wherein, γ is the design variable, and b is a real number greater than 0.2 and less than 0.8; The three-dimensional geometric design model is obtained according to the spatial distribution of the design variable values ​​after filtering.

6. The method for designing an inkjet printing device according to claim 5, characterized in that: Acquiring a three-dimensional geometric design model according to the spatial distribution of the design variable values ​​after filtering, including: According to the spatial distribution of the design variable values ​​after filtering, an interpolation fitting is performed on the contour of the spatial distribution of the design variable values ​​characterizing the absence of solid material to obtain a two-dimensional geometric contour; A three-dimensional geometric design model is obtained according to the two-dimensional geometric outline.

7. An inkjet printing device, characterized in that: The inkjet printing device is designed and manufactured using the design method of the inkjet printing device according to any one of claims 1 to 6, and the inkjet printing device comprises: A liquid supply pool, a pressure chamber and a flow limiting portion, wherein the flow limiting portion includes a flow limiting portion inlet area and a flow limiting portion straight end, wherein the flow limiting portion inlet area is connected to the outlet of the liquid supply pool, and the outlet of the flow limiting portion straight end is connected to the inlet of the pressure chamber; A drainage structure and a spraying structure, the outlet of the pressure chamber is connected to the inlet of the drainage structure, and the outlet of the drainage structure is connected to the spraying structure; wherein the outlet of the pressure chamber is the same in shape and size as the inlet of the drainage structure, and the outlet diameter of the drainage structure is larger than the diameter of the spraying structure.

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