Online regulation and control method and system for deformation of base plate of air floating platform

Abstract

The invention belongs to the related technical field of printing display, and particularly relates to an air floating platform substrate deformation online regulation and control method and system, and the method comprises the steps: synchronously collecting the change data of the flying height of a substrate at preset m measurement points in real time; constructing a modal superposition equation based on the flight height change data corresponding to each measuring point and the values of the n modal shape functions at the measuring point; solving the equation set to obtain a time coordinate set of each modal at the collection moment; based on the set and the value of the n modal shape functions at each target point, obtaining the change data of the flying height of the substrate at the target point, and carrying out closed-loop control; and determining n modal shape functions: regarding the whole gas film covered by the target substrate as an elastic foundation, constructing a gas film stiffness distribution function through fitting, and combining an orthogonal function meeting boundary conditions to obtain a mass matrix and a stiffness matrix of the gas film-substrate assembly, thereby calculating the modal shape functions of the n gas film-substrate assemblies. The device can realize online regulation and control.

Description

Technical Field

[0001] The present invention belongs to the technical field related to printing display, and more specifically, relates to an on-line regulation method and system for substrate deformation of an air-floating platform. Background Art

[0002] The new display inkjet printing technology uses an additive manufacturing method to deposit a solution into pixel pits, thereby forming light-emitting pixels and encapsulation films. Compared with the traditional vacuum evaporation process, it can effectively avoid the waste of solvents and solutes. In particular, the inkjet printing process can be freely patterned and is especially suitable for large-size panels. One of the key links in the inkjet printing manufacturing of large-size flexible panels is the air-floating transportation of flexible substrates. The vibration and deformation during transportation will directly affect the printing accuracy. Being able to detect and control the accuracy of air-floating transportation during transportation will be able to greatly improve the yield of the inkjet printing system, which is conducive to promoting the mass production application of inkjet printing technology in the field of new displays, and is an urgent goal to be broken through by global panel manufacturers and research institutions.

[0003] The air-floating transportation of large-size flexible substrates has the advantages of non-contact and light load, but at the same time, it also introduces new challenges and problems. A patent CN202311618114 describes a spliced air-floating platform and an inkjet printing device for display panel processing. However, it only proposes a new structural design scheme without proposing a corresponding detection and control scheme. Patent CN115435742A describes a continuous on-line warpage rapid measurement device for substrate glass. This method proposes a structural design scheme to measure the deformation of a freely suspended glass substrate. Obviously, this method cannot be applied to a moving air-floating substrate.

[0004] Further research finds that the technologies designed in existing patents and literatures still have the following deficiencies:

[0005] 1. For large-size flexible glass substrates transported by air-floating, during the movement of the glass, some existing mechanical design schemes are only applicable to substrates in a freely suspended state and cannot be applied in this scenario.

[0006] 2. For high-precision air-floating transportation scenarios, the stability and reliability of air-floating transportation are also key indicators. A complete closed-loop regulation scheme is required to ensure accuracy and improve the adaptability of the air-floating platform, which is not considered in existing schemes.

[0007] 3. Existing schemes are mostly structural design and improvement schemes for air-floating platforms. This scheme has strong pertinence and is difficult to be actually applied. There is no detection and control scheme that does not overly rely on the structure and can be conveniently applied in various scenarios. Summary of the Invention

[0008] In view of the above defects or improvement requirements of the prior art, the present invention provides an on-line regulation method and system for the deformation of the air-bearing platform substrate, aiming to realize the on-line regulation of the deformation of the air-bearing platform substrate in the actual printing scenario without relying on the platform structure.

[0009] To achieve the above object, according to one aspect of the present invention, there is provided an on-line regulation method for the deformation of the air-bearing platform substrate, including:

[0010] During the inkjet printing process, the change data of the substrate flying height at m preset measuring points are collected in real time and synchronously; based on the flying height change data corresponding to each measuring point and the values of n modal shape functions at the measuring point, a modal superposition equation is constructed; based on the modal superposition equations of all measuring points, by solving the equations, the sets of modal time coordinates η1(t), η2(t),..., η n (t) at the acquisition time t are obtained; based on the set of time coordinates and the values of n modal shape functions at each target point, the change data of the substrate flying height at the target point are obtained;

[0011] Based on the change data of the substrate flying height at all target points, closed-loop control is performed to realize the on-line regulation of the deformation of the air-bearing platform substrate;

[0012] Among them, the n modal shape functions are determined in the following way: regarding the overall air film covered by the target substrate as an elastic foundation, the air film stiffness distribution function is constructed by fitting and combined with the orthogonal function satisfying the boundary conditions to obtain the mass matrix and stiffness matrix of the air film-substrate assembly; based on the mass matrix and stiffness matrix, n modal shape functions of the air film-substrate assembly are calculated.

[0013] Further, the construction method of the air film stiffness distribution function is as follows:

[0014] Measure the air film stiffness of each independently supplied air-bearing block of the air-bearing platform;

[0015] Using the air film stiffness and coordinate positions of each air-bearing block for function fitting, the air film stiffness distribution function k(x, y) of the overall air film covered by the target substrate is obtained, where the air film stiffness corresponding to each position within each air-bearing block is the same, and the air film stiffness corresponding to the gap between air-bearing blocks is zero.

[0016] Further, the method for calculating n modal shape functions of the air film-substrate assembly based on the mass matrix and stiffness matrix is as follows:

[0017] Based on the mass matrix and stiffness matrix of the air film - substrate assembly, determine the set of natural frequencies of the target substrate in the air - floating state and the set of modal shape functions with respect to the coordinate positions, and select the n modal shape functions corresponding to the n smallest natural frequencies from the set of modal shape functions. Here, one natural frequency and its corresponding modal shape function form a mode.

[0018] Furthermore, by using each air - floating block to support and suspend substrates of different thicknesses or adding weight loads on the suspended glass substrate, the air - film stiffness measurement of the air - floating block is realized. Among them, the air - film stiffness of each air - floating block is calculated by the following formula:

[0019]

[0020] In the formula, ΔG represents the change in gravity in two measurements, and Δh represents the change in the flying height of the substrate in two measurements.

[0021] Furthermore, the element in the i - th row and j - th column of the mass matrix M of the air - film - substrate assembly is:

[0022]

[0023] The element in the i - th row and j - th column of the stiffness matrix K is:

[0024]

[0025] In the formula, ρ is the density of the target substrate, and H is the thickness of the target substrate; when the substrate is adsorbed on one side during transportation, φ i is the i - th order modal function of the cantilever plate, and φ j (x, y) is the j - th order modal function of the cantilever plate; when it is adsorbed on both sides, φ i is the i - th order modal function of the plate with opposite sides fixed and opposite sides free, and φ j (x, y) is the j - th order modal function of the plate with opposite sides fixed and opposite sides free; a and b respectively represent the length and width of the substrate, represents the Laplace operator;

[0026] By solving the formula: The set of natural frequencies λ1, …, λ i , …, λ n and its corresponding set of mode - shape functions W1(x, y), …, W i (x, y), … W n (x, y) are obtained.

[0027] Furthermore, the modal superposition equations corresponding to each measurement point are respectively:

[0028] η1(t)W1(x1, y1)+η2(t)W2(x1, y1)+...+η n(t)W n (x1,y1) = w(x1,y1)

[0029] η1(t)W1(x2,y2) + η2(t)W2(x2,y2) +... + η n (t)W n (x2,y2) = w(x2,y2)

[0030]

[0031] η1(t)W1(x m ,y m ) + η2(t)W2(x m ,y m ) +... + η n (t)W n (x m ,y m ) = w(x m ,y m )

[0032] Wherein, w(x1,y1), w(x2,y2), …, w(x m ,y m ) respectively represent the change data of the substrate flying height at different measuring points; W1(x1,y1), W2(x1,y1), W n (x1,y1) respectively represent the values of different modal shape functions at the first measuring point; W1(x2,y2), W2(x2,y2), W n (x2,y2) respectively represent the values of different modal shape functions at the second measuring point; W1(x m ,y m ), W2(x m ,y m ), W n (x m ,y m ) respectively represent the values of different modal shape functions at the m-th measuring point.

[0033] According to another aspect of the present invention, an on-line regulation system for substrate deformation of an air-floating platform is provided, including: a displacement sensor, a processor and an actuator;

[0034] Wherein, the displacement sensor is used to synchronously collect in real time the change data of the substrate flying height at m preset measuring points during the inkjet printing process;

[0035] The processor is configured to construct a modal superposition equation based on the flying height change data corresponding to each measurement point and the values of n modal shape functions at the measurement point; based on the modal superposition equations of all measurement points, by solving the system of equations, obtain the sets of modal time coordinates η1(t), η2(t),..., η n (t) at the acquisition time t; based on the set of time coordinates and the values of n modal shape functions at each target point, obtain the change data of the flying height of the substrate at the target point; based on the change data of the flying height of the substrate at all target points, obtain the air pressure setting value of the target air bearing block;

[0036] The actuator is configured to perform closed-loop control based on the air pressure setting values of the target air bearing blocks.

[0037] Furthermore, the actuator includes a positive pressure proportional valve in the unloading area, a negative pressure proportional valve in the unloading area, a positive pressure proportional valve in the precision area, a negative pressure proportional valve in the precision area, a positive pressure proportional valve in the loading area, and a negative pressure proportional valve in the loading area.

[0038] Furthermore, the displacement sensor is a laser sensor.

[0039] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the technical solution provided by the present invention mainly has the following beneficial effects:

[0040] 1. The present invention proposes an on-line regulation method for the deformation of the air-bearing platform substrate. By simplifying the complex air-bearing dynamic system, it provides a convenient framework for the design of the control system. The air-bearing system is usually a multi-degree-of-freedom system, and its dynamic behavior may be very complex. Considering that the vibration modes of this system are usually non-linear and coupled, the present invention proposes to regard the overall air film covered by the target substrate as an elastic foundation. By fitting to construct the air film stiffness distribution function and combining with the orthogonal function satisfying the boundary conditions, the mass matrix and stiffness matrix of the air film-substrate assembly are obtained. Based on the mass matrix and stiffness matrix, n modal shape functions of the air film-substrate assembly are calculated, that is, the present invention proposes that the motion (or vibration) of a complex multi-degree-of-freedom system can be simplified into a series of independent "modal" vibration modes that can be analyzed and controlled separately. The motion (or vibration) of a complex multi-degree-of-freedom system is decomposed into several simplified and independent "modes". Each mode is the inherent natural vibration form of the system, and each mode has an independent natural frequency, vibration mode, and amplitude. Further, by constructing a modal superposition equation to determine the change in the flying height of the substrate at each target point, the deformation of the substrate is regulated online. Therefore, the present invention can realize the on-line regulation of the deformation of the air-bearing platform substrate in the actual printing scenario on the moving air-bearing substrate without relying on the platform structure.

[0041] 2. The present invention proposes a method for constructing an air film stiffness distribution function, specifically by measuring the air film stiffness of each independently air-supplied air bearing block of the air-bearing platform; using the air film stiffness and coordinate positions of each air bearing block for function fitting to obtain the air film stiffness distribution function k(x, y) of the overall air film covered by the target substrate. Among them, the air film stiffness corresponding to each position within each air bearing block is consistent, and the air film stiffness corresponding to the gap between air bearing blocks is zero. This method can be applied to air-bearing platform systems with any arrangement, any area, and any structure, realizing the equivalent modeling of the air-bearing platform.

[0042] 3. The present invention proposes a preferred method for determining n modal vibration shape functions based on two matrices, specifically based on the mass matrix and stiffness matrix of the air film - substrate assembly to determine the set of natural frequencies of the target substrate in the air-bearing state and the set of modal vibration shape functions with respect to coordinate positions, and selecting n modal vibration shape functions corresponding to the first n minimum natural frequencies from the set of modal vibration shape functions. This method ensures the effective implementation of online regulation. This method can flexibly determine the modal vibration shape functions according to the requirements of target detection accuracy to reduce the measurement cost and calculation scale, and is applicable to a variety of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flowchart of a method for online regulation of the deformation of the air-bearing platform substrate provided by an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the detection point positions provided by an embodiment of the present invention;

[0045] Figure 3 is a schematic diagram of the closed-loop regulation scheme provided by an embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of the air film stiffness test scheme provided by an embodiment of the present invention;

[0047] Figure 5 is a composition diagram of an online regulation system for the deformation of the air-bearing platform substrate provided by an embodiment of the present invention.

[0048] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0049] 1 is PC1, 2 is PLC, 3 is the positive pressure proportional valve in the blanking area, 4 is the negative pressure proportional valve in the blanking area, 5 is the positive pressure proportional valve in the precision area, 6 is the negative pressure proportional valve in the precision area, 7 is the laser displacement sensor, 8 is the positive pressure proportional valve in the loading area, 9 is the negative pressure proportional valve in the loading area, 10 is the air-bearing motor guide rail, 11 is the substrate adsorption module, 12 is the air-bearing module in the blanking area, 13 is the air-bearing module in the precision area, and 14 is the air-bearing module in the loading area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] Embodiment 1

[0052] An on-line regulation method for the deformation of the air-bearing platform substrate, as Figure 1 shown, includes:

[0053] During the inkjet printing process, the change data of the substrate flying height at m preset measuring points is collected in real time and synchronously; based on the flying height change data corresponding to each measuring point and the values of n modal shape functions at this measuring point, a modal superposition equation is constructed; based on the modal superposition equations of all measuring points, by solving the system of equations, the sets of modal time coordinates η1(t), η2(t),..., η n (t) at the acquisition time t are obtained; based on the set of time coordinates and the values of n modal shape functions at each target point, the change data of the substrate flying height at this target point is obtained;

[0054] Based on the change data of the substrate flying height at all target points, closed-loop control is performed to realize on-line regulation of the deformation of the air-bearing platform substrate;

[0055] Among them, the n modal shape functions are pre-determined in the following way:

[0056] n modal shape functions of the air film-substrate assembly are preset, and the determination method is: regarding the overall air film covered by the target substrate as an elastic foundation, by fitting to construct an air film stiffness distribution function and combining with orthogonal functions that satisfy the boundary conditions, the mass matrix and stiffness matrix of the air film-substrate assembly are obtained; based on the mass matrix and stiffness matrix, n modal shape functions of the air film-substrate assembly are calculated.

[0057] Online regulation is performed by presetting n modal shape functions. In the prior art, the adjustment of the air-bearing platform often adopts manual initial adjustment. Under the influence of factors such as the flatness of the platform and the change of the air supply pressure, the leveling of the air bearing is very cumbersome and cannot adaptively and actively regulate the air bearing state.

[0058] In addition, there are many factors causing substrate deformation, including different deformations due to different air film thicknesses under the target substrate.

[0059] Regarding the selection of the number and positions of the measuring points, as Figure 2 shown, the following principles should be followed:

[0060] 1) The number of measurement points should be greater than the number of selected modes. It is recommended that the number of selected modes ≥ 4;

[0061] 2) The positions of the measurement points should be arranged to avoid the node positions of the mode shape functions. The nodes are the zeros of the mode shape W i (x, y) functions;

[0062] 3) Try to select asymmetric points on the plate for the measurement points, and arrange the measurement points as scattered as possible;

[0063] 4) The more the number of selected modes, the more accurate the reconstruction accuracy. The specific number of selected modes should be determined through actual experiments in combination with the target accuracy requirements.

[0064] The method of this embodiment is a closed-loop control scheme. The displacement data of each measurement point is obtained. The PC combines the measured data with the stored mode shape functions and corresponding algorithms to obtain the estimated result of the deformation of the entire surface. According to the deformation, control instructions are sent to regulate the actuator to achieve the control of the deformation of the air-bearing platform. The detection of the displacement sensor is carried out in real time to form a closed-loop feedback. One implementation is as Figure 3 shown,

[0065] As a preferred implementation, the n mode shape functions are preferably determined by the following method:

[0066] Measure the air film stiffness of each independently air-supplied air-bearing block of the air-bearing platform;

[0067] Use the air film stiffness and coordinate positions of each air-bearing block for function fitting to obtain the air film stiffness distribution function k(x, y) of the overall air film covered by the target substrate. Among them, the air film stiffness corresponding to each position within each air-bearing block is the same, and the air film stiffness corresponding to the gap between air-bearing blocks is zero;

[0068] Based on the air film stiffness distribution function and combined with orthogonal functions that satisfy the boundary conditions, calculate the mass matrix and stiffness matrix of the air film-substrate assembly to determine the set of natural frequencies of the target substrate in the air-bearing state and the set of mode shape functions with respect to the coordinate positions, and select the n mode shape functions corresponding to the first n smallest natural frequencies from the set of mode shape functions. Among them, one natural frequency and its corresponding one mode shape function constitute a mode.

[0069] When all natural frequencies and mode shape functions are calculated, store the natural frequency results and mode shape function data in ascending order of natural frequency. One natural frequency and its corresponding mode shape constitute a mode. Select the n mode shape functions corresponding to the first n smallest natural frequencies for online regulation.

[0070] As a preferred implementation, such as Figure 4As shown, the air film stiffness of each air bearing block is measured by using each air bearing block to support and suspend substrates of different thicknesses or adding a weight load on the suspended glass substrate. Among them, the air film stiffness of each air bearing block is calculated by the following formula:

[0071]

[0072] In the formula, ΔG represents the change in gravity in two measurements, and Δh represents the change in the flying height of the substrate in two measurements.

[0073] As a preferred embodiment, the element in the i-th row and j-th column of the mass matrix M of the air film - substrate assembly is:

[0074]

[0075] The element in the i-th row and j-th column of the stiffness matrix K is:

[0076]

[0077] In the formula, ρ is the density of the target substrate, and H is the thickness of the target substrate; when the substrate is adsorbed on one side during transportation, φ i is the i-th order mode function of the cantilever plate, and φ j (x, y) is the j-th order mode function of the cantilever plate; when it is adsorbed on both sides, φ i is the i-th order mode function of the plate with opposite sides fixed and opposite sides free, and φ j (x, y) is the j-th order mode function of the plate with opposite sides fixed and opposite sides free; a and b respectively represent the length and width of the substrate, and ▽ represents the Laplace operator;

[0078] By solving the formula: the set of natural frequencies λ1, …, λ i , …, λ n and its corresponding set of mode shape functions W1(x, y), …, W i (x, y), … W n (x, y) are obtained.

[0079] As a preferred embodiment, the modal superposition equations corresponding to each measurement point are respectively:

[0080] η1(t)W1(x1, y1) + η2(t)W2(x1, y1) +... + η n (t)W n (x1, y1) = w(x1, y1)

[0081] η1(t)W1(x2, y2) + η2(t)W2(x2, y2) +... + η n (t)W n (x2, y2) = w(x2, y2)

[0082]

[0083] η1(t)W1(x m ,y m ) + η2(t)W2(x m ,y m ) +... + η n (t)W n (x m ,y m ) = w(x m ,y m )

[0084] In the formula, w(x1, y1), w(x2, y2), …, w(x m ,y m ) respectively represent the change data of the flying height of the substrate at different measurement points; W1(x1, y1), W2(x1, y1), W n (x1, y1) respectively represent the values of different modal shape functions at the first measurement point; W1(x2, y2), W2(x2, y2), W n (x2, y2) respectively represent the values of different modal shape functions at the second measurement point; W1(x m ,y m ), W2(x m ,y m ), W n (x m ,y m ) respectively represent the values of different modal shape functions at the mth measurement point.

[0085] For example, the deformation amount w(x a ,y a ) of the target point (x a ,y a ) is:

[0086] w(x a ,y a ) = η1(t)W1(x a ,y a ) + η2(t)W2(x a ,y a ) +... + η n (t)W n (x a ,y a )

[0087] Divide the entire surface of the substrate into grids with equal spacing, and the deformation result of the entire surface can be obtained by calculating the deformation of each grid node.

[0088] The method of this embodiment is based on regarding the overall air film covered by the target substrate as an elastic foundation, and modeling to construct a modal superposition equation. In theory, any solution can be achieved through a set of orthogonal bases. Modal decoupling is an intrinsic property of the system. Starting from the basis of modal theory, this embodiment proposes an optimal operation process and calculation method for this scenario.

[0089] Embodiment 2

[0090] An on-line regulation system for the deformation of the substrate of an air-bearing platform, comprising: a displacement sensor, a processor and an actuator; wherein, the displacement sensor is used to synchronously collect the change data of the flying height of the substrate at m preset measuring points in real time during the inkjet printing process; the processor is used to construct a modal superposition equation based on the flying height change data corresponding to each measuring point and the values of n modal shape functions at this measuring point; based on the modal superposition equations of all measuring points, by solving the system of equations, obtain the sets of modal time coordinates η1(t), η2(t),..., η n (t) at the acquisition time t; based on the set of time coordinates and the values of n modal shape functions at each target point, obtain the change data of the flying height of the substrate at this target point; based on the change data of the flying height of the substrate at all target points, obtain the air pressure setting value of the target air-bearing block; the actuator is used to perform closed-loop control based on the air pressure setting values of each target air-bearing block.

[0091] As a preferred implementation manner, the actuator includes a positive pressure proportional valve in the blanking area, a negative pressure proportional valve in the blanking area, a positive pressure proportional valve in the precision area, a negative pressure proportional valve in the precision area, a positive pressure proportional valve in the loading area, and a negative pressure proportional valve in the loading area. It can be flexibly divided and set according to the actual situation.

[0092] As a preferred implementation manner, the displacement sensor is a laser sensor.

[0093] A specific implementation scheme, as Figure 5 shown, the system consists of a PC 1, a PLC (controller) 2, a positive pressure proportional valve 3 in the blanking area, a negative pressure proportional valve 4 in the blanking area, a positive pressure proportional valve 5 in the precision area, a negative pressure proportional valve 6 in the precision area, a laser displacement sensor 7, a positive pressure proportional valve 8 in the loading area, a negative pressure proportional valve 9 in the loading area, an air-bearing motor guide rail 10, a substrate adsorption module 11, a blanking area air-bearing module 12, a precision area air-bearing module 13, and a loading area air-bearing module 14.

[0094] Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An online control method for deformation of an air floating platform substrate, characterized in that: include: During the inkjet printing process, the change data of the substrate flying height at the preset m measuring points are collected synchronously in real time; Based on the flight height change data corresponding to each measuring point and the values ​​of the modal vibration function of the n air film-substrate assemblies at the measuring point, the modal superposition equation of the air film-substrate assembly is constructed; based on the modal superposition equation of all measuring points, the time coordinate set of each mode at the acquisition time t is obtained by solving the equation group. n (t); based on the time coordinate set and the values ​​of the n modal vibration shape functions at each target point, obtain the change data of the substrate flying height at the target point; Closed-loop control is performed based on the change data of the substrate flying height at all target points to achieve online regulation of the deformation of the air-floating platform substrate; Among them, the n modal vibration functions are determined in the following way: the overall air film covered by the target substrate is regarded as an elastic foundation, the air film stiffness distribution function is constructed by fitting and combined with the orthogonal function that satisfies the boundary conditions, so as to obtain the mass matrix and stiffness matrix of the air film-substrate assembly; based on the mass matrix and stiffness matrix, the modal vibration functions of the n air film-substrate assemblies are calculated.

2. The method for online control of deformation of an air floating platform substrate according to claim 1, characterized in that: The air film stiffness distribution function is constructed as follows: Measure the air film stiffness of each independently supplied air flotation block of the air flotation platform; The air film stiffness and coordinate position of each air floating block are used for function fitting to obtain the air film stiffness distribution function k(x,y) of the overall air film covered by the target substrate, where the air film stiffness corresponding to each position in each air floating block is consistent, and the air film stiffness corresponding to the gap between the air floating blocks is zero.

3. The method for online control of deformation of an air floating platform substrate according to claim 1, characterized in that: The method of calculating the modal vibration function of n air film-substrate assemblies based on the mass matrix and stiffness matrix is: Based on the mass matrix and stiffness matrix of the air film-substrate assembly, the natural frequency set of the target substrate in the air floating state and the modal vibration shape function set about the coordinate position are determined, and n modal vibration shape functions corresponding to the first n minimum natural frequencies are selected from the modal vibration shape function set, where a natural frequency and its corresponding modal vibration shape function constitute a mode.

4. The method for online control of deformation of an air floating platform substrate according to claim 2, characterized in that: By using each air floating block to support and suspend substrates of different thicknesses or to add a weight load on the suspended glass substrate, the air film stiffness of the air floating block can be measured; wherein the air film stiffness of each air floating block is calculated by the following formula: Where ΔG represents the change in gravity between two measurements, and Δh represents the change in the flying height of the substrate between two measurements.

5. The method for online control of deformation of an air floating platform substrate according to claim 3, characterized in that: The element in the i-th row and j-th column of the mass matrix M of the air film-substrate assembly is: The element in the i-th row and j-th column of the stiffness matrix K is: Where ρ is the density of the target substrate, H is the thickness of the target substrate; when the substrate is unilaterally adsorbed during transportation, φ i is the i-th order mode function of the cantilever plate, φ j (x, y) is the jth mode function of the cantilever plate; when it is double-sided adsorption, φ i is the i-th mode function of the opposite side fixed and opposite side free plate, φ j (x, y) is the jth mode function of the opposite edge fixed and opposite edge free plate; a and b represent the length and width of the substrate, respectively, and ▽ represents the Laplace operator; By solving the formula: Get the natural frequency set λ1,…,λ i , …,λ n and its corresponding vibration mode function set W1(x,y),…,W i (x,y),…W n (x,y).

6. The method for online control of deformation of an air floating platform substrate according to claim 1, characterized in that: The modal superposition equations corresponding to each measuring point are: In the formula, w(x1,y1),w(x2,y2),…,w(x m ,y m ) represent the change data of substrate flying height at different measuring points; W1(x1,y1), W2(x1,y1), W n (x1, y1) represent the values ​​of the different mode vibration functions at the first measuring point; W1(x2, y2), W2(x2, y2), W n (x2, y2) represent the values ​​of different modal vibration functions at the second measuring point; W1(x m ,y m )、W2(x m ,y m )、W n (x m ,y m ) represent the values ​​of different mode vibration shape functions at the mth measuring point.

7. An online control system for deformation of an air floating platform substrate, characterized in that: include: displacement sensors, processors, and actuators; The displacement sensor is used to synchronously collect the change data of the substrate flying height at the preset m measuring points in real time during the inkjet printing process; The processor is used to construct a modal superposition equation based on the flight height change data corresponding to each measuring point and the values ​​of n modal vibration shape functions at the measuring point; based on the modal superposition equations of all measuring points, by solving the equation group, the modal time coordinate sets η1(t), η2(t), ..., η at the acquisition time t are obtained. n (t); based on the time coordinate set and the values ​​of the n modal vibration shape functions at each target point, obtain the change data of the substrate flying height at the target point; based on the change data of the substrate flying height at all target points, obtain the air pressure setting value of the target air floating block; The actuator is used to perform closed-loop control based on the air pressure setting value of each target air floating block.

8. The air floating platform substrate deformation online control system according to claim 7, characterized in that: The actuator includes a positive pressure proportional valve in the unloading area, a negative pressure proportional valve in the unloading area, a positive pressure proportional valve in the precision area, a negative pressure proportional valve in the precision area, a positive pressure proportional valve in the loading area and a negative pressure proportional valve in the loading area.

9. The air floating platform substrate deformation online control system according to claim 7, characterized in that: The displacement sensor is a laser sensor.

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