Curved surface printing color register method and device and storage medium

Abstract

The invention discloses a curved surface printing color register method, curved surface printing color register equipment and a storage medium. The method comprises the following steps: S1, collecting curved surface data; s2, constructing a mathematical model capable of accurately representing the geometric characteristics of the curved surface; s3, acquiring a printing starting point of the digital printer; s4, printing the printing information of the nozzle; s5, generating printing data corresponding to the curved surface from the original image by calculating projection; s6, the printing data calculated in the step S5 are sent to a printer, and curved surface printing is started; the problem that a plane printer cannot print the curved surface is solved, the purpose that the printing data corresponding to the curved surface is generated from the original image through calculation projection so that the plane printer can be used for printing the curved surface is achieved, and the universality and the flexibility are high. The device is suitable for various polygonal curved surfaces and can be operated in a regular or irregular manner, the movement plane of the spray head can be flexibly set as required, and different printing tasks and creative design requirements can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of printers, and in particular to a curved surface printing color matching method, equipment and storage medium. Background Art

[0002] In the current digital printing field, the design of mainstream digital printers is mostly based on flat printing media. Its conventional working mode is to realize image printing on flat paper, film and other media by means of a carriage with a printhead mounted on it to perform reciprocating scanning motion on a linear guide rail. This mechanical structure and printing method has been able to achieve high accuracy and efficiency in flat printing tasks, meeting many conventional printing needs, such as document printing, flat image output, etc.

[0003] However, when faced with special application scenarios that require printing on uneven curved media, many new challenges arise. Due to the irregularity of the surface itself, the geometric relationship between its various positions and the nozzle, such as the distance and angle, is constantly changing, which is completely different from the relatively fixed and regular position relationship between the nozzle and the medium during flat printing. If the existing flat printing data and printing method are directly used, the ink droplets ejected by the nozzle will inevitably not fall accurately at the expected position, which will lead to serious deviations in color registration, ultimately affecting the quality of the printed image, and may even make the entire printing task unable to achieve the expected effect. Moreover, considering the premise that the mechanical structure of the existing printer is not greatly changed, it means that it is impossible to directly adapt to curved surface printing by adjusting the hardware on a large scale (such as changing the shape of the guide rail, adding complex curved surface adaptation mechanical devices, etc.), so the only solution can be found from the printing data level. By making clever and precise changes to the printing data, the limitations of the mechanical structure can be compensated to ensure that the ink droplets of different color nozzles of the nozzle can fall as far as possible on the uneven surface. The expected position, achieve correct color registration and high-quality print output.

[0004] Therefore, there is an urgent need for a curved surface printing color matching method that can generate printing data of the corresponding curved surface from the original image through calculation projection, so as to perform curved surface printing using a flat printer. Summary of the invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a curved surface printing color matching method, device and storage medium.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A curved surface printing color registration method comprises the following steps:

[0008] S1, collect surface data, measure the uneven surface to be printed through image recognition technology, and obtain the three-dimensional coordinate data of each point on the surface;

[0009] S2, using mathematical modeling algorithms to construct a mathematical model that can accurately characterize the geometric characteristics of the surface;

[0010] S3, obtaining information of the printing starting point of the digital printer, the total number of passes of the printed image, and the scanning range of each pass;

[0011] S4, obtaining printing information of the print head through a digital printer, specifically including the number of print heads, the geometric arrangement of each print head, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle;

[0012] S5, based on step S3 and step S4, generating printing data of the corresponding surface from the original image by calculating the projection;

[0013] S6, sending the printing data calculated in step S5 to the printer to start curved surface printing.

[0014] Preferably, step S1 is specifically to use laser scanning technology to scan the curved surface line by line using a laser beam, capture the reflected light signal through a high-precision optical signal receiving device, and accurately obtain the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information of the change in the intensity of the reflected light; or use structured light projection technology to project a preset specific light pattern onto the curved surface, and according to the deformation characteristics of the light pattern on the curved surface, use the principle of triangulation to carefully deduce the spatial position details of each point.

[0015] Preferably, the step S2 specifically comprises using a mathematical modeling algorithm to construct a mathematical model that can accurately characterize the geometric features of the surface through a method based on surface fitting or spline function.

[0016] Preferably, the modeling accuracy of the mathematical model matches the printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the adjacent interval of printed pixels.

[0017] Preferably, the step S3 specifically includes, based on the driving of the print head of the printer itself, obtaining the printing track of printing on a flat surface when printing the curved surface image, determining the printing starting point, the total number of passes of the printed image, and the scanning range of each pass;

[0018] Preferably, the calculation projection method is as follows:

[0019] S51, obtaining vertex coordinates of the entire polygonal surface through a mathematical model, specifically including coordinates of all vertices on the surface;

[0020] S52, calculate the nozzle motion plane. In order to accurately describe the nozzle motion plane, the following plane equation form is used to express it. There are two planes, and their equations are recorded as follows:

[0021] Ax+By+Cz+D=0,

[0022] A′x+B′y+C′z+D′=0,

[0023] Where (A, B, C), (A′, B′, C′) are the normal vectors of the plane, and D and D′ are constant terms;

[0024] S53, obtaining the printing resolution of the original image;

[0025] S54, for any given point P (x, y, z) on the surface, the vertical distance d from point P to the plane can be calculated by the following formula:

[0026] d=∣Ax+By+Cz+D∣A2+B2+C2;

[0027] The calculation formula for the vertical distance d' from another point P'(x, y, z) on the surface to this plane is:

[0028] d′=A′2+B′2+C′2∣A′x+B′y+C′z+D′∣;

[0029] S55, the calculated distance dd' is moved from the point P(x,y,z)P'(x,y,z) on the surface to the plane by the distance dd' along the direction of the plane normal vector (A,B,C)(A',B',C'), and the projection point P is obtained. m (x m ,y m ,z m ) m ′(x m ,y m ,z m ). The direction of movement is the opposite of the vector (A, B, C)(A′, B′, C′), that is, (-A, -B, -C)(-A′, -B′, -C′). Therefore, the coordinate calculation formula of the projection point is:

[0030] x m =x+AA2+B2+C2·dx m =x+A2+B2+C2A·d;

[0031] y m =y+BA2+B2+C2·dy m =y+A2+B2+C2B·d;

[0032] z m =y+CA2+B2+C2·dz m =y+A2+B2+C2C·d;

[0033] S56, applying step S55 to all coordinate vertices obtained in step S51;

[0034] S57, according to the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle hole at each pass position of the nozzle to generate printing data.

[0035] A curved surface printing color matching device comprises at least one processor, at least one memory and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the above-mentioned curved surface printing color matching method is implemented.

[0036] A storage medium stores computer program instructions, wherein the computer program instructions are executed by a processor to implement the above-mentioned curved surface printing color matching method.

[0037] The present invention solves the problem that a flat printer cannot print curved surfaces, and realizes the purpose of using a flat printer to print curved surfaces by generating printing data of the corresponding curved surface from the original image through calculation projection, and the present invention has strong versatility and flexibility. It is applicable to a variety of polygonal curved surfaces, whether regular or irregular. The movement plane of the nozzle can be flexibly set as needed, which can meet different printing tasks and creative design requirements, adapt to various application scenarios, and has scalability. It can be combined with images of different resolutions and can be easily applied as printing technology develops and accuracy requirements change. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of a curved surface printing color matching method of the present invention. DETAILED DESCRIPTION

[0039] In order to further explain the technical means and effects taken by the present invention to achieve the predetermined invention purpose, exemplary embodiments will be described in detail here, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are only examples of methods and systems consistent with some aspects of the present application as detailed in the attached claims.

[0040] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0041] Example 1

[0042] The present invention provides a curved surface printing color registration method, comprising the following steps:

[0043] S1, collect surface data, measure the uneven surface to be printed through image recognition technology, and obtain the three-dimensional coordinate data of each point on the surface;

[0044] In step S1, advanced and precise measurement technology is used to collect surface data. Specifically, it can be achieved through the following two preferred methods: First, laser scanning technology is used to scan the surface line by line using a laser beam with high energy density and good directionality, and a high-precision optical signal receiving device is equipped, which can keenly capture reflected light signals. Based on the time difference principle of light propagation and information such as changes in the intensity of reflected light, the three-dimensional coordinate data of each point on the surface is accurately obtained through professional data processing algorithms. Second, using structured light projection technology, a preset specific light pattern is projected onto the surface. Due to the uneven surface, the light pattern will be deformed accordingly. Then, based on the deformation characteristics of the light pattern on the surface, with the help of mature triangulation principles, the spatial position details of each point are carefully deduced through precise geometric calculations. Through the above methods, it is ensured that the collected surface data can fully and accurately reflect the actual geometric shape of the surface, laying a solid data foundation for subsequent steps;

[0045] S2, using advanced mathematical modeling algorithms to construct a mathematical model that can accurately characterize the geometric characteristics of the surface;

[0046] In step S2, advanced mathematical modeling algorithms are used, specifically through mature mathematical methods such as surface fitting or spline functions, to conduct in-depth analysis and processing of the three-dimensional coordinate data of a large number of points on the surface obtained in step S1. Through surface fitting, according to the distribution law of data points, the most suitable mathematical function is found to describe the overall shape of the surface; or the spline function is used to divide the surface into multiple local areas, and a suitable function expression is constructed in each area, so that the overall model can accurately reflect the complex shape of the surface and ensure a smooth transition between the local areas. The mathematical model constructed in this way can accurately characterize the geometric characteristics of the surface, covering key information such as the curvature change, concave-convex distribution and overall shape category of the surface, and requires that the modeling accuracy and printing accuracy of the mathematical model match, ensuring that the coordinate interval of each polygon vertex in the model is less than or equal to the adjacent interval of the printed pixels, providing a reliable basis for subsequent operations such as printing data generation based on the model, and avoiding printing errors caused by precision differences;

[0047] S3, obtaining information of the printing starting point of the digital printer, the total number of passes of the printed image, and the scanning range of each pass;

[0048] In step S3, the printer's print head driving mechanism is deeply analyzed, and the relevant information of the printing trajectory when the curved surface image is simulated as a flat print is obtained by reading the relevant parameters and control logic inside the printer. Specifically, determine the printing starting point, that is, the initial position coordinates where the nozzle starts the printing operation; clarify the total number of passes for the printed image. This parameter reflects the number of times the nozzle scans the image during the entire printing process, and reflects the number of printed layers and the degree of coverage; at the same time, grasp the scanning range of each pass, that is, the area that the nozzle can cover during each scanning process, including the horizontal and vertical interval definitions. This information will serve as an important basis for the subsequent generation of printing data for adapting to the surface and planning the nozzle movement path, ensuring that the printing data can accurately correspond to the actual working conditions of the printer and achieve a reasonable match between the printed image and the curved surface;

[0049] S4, obtaining printing information of the print head through a digital printer, specifically including the number of print heads, the geometric arrangement of each print head, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle;

[0050] In step S4, data is interacted with the digital printer to obtain comprehensive and detailed printing information of its print heads. First, the number of nozzles is clarified, and the number of nozzles involved in the printing work is determined. Different numbers of nozzles will affect the printing efficiency and color combination methods, etc.; further understand the geometric arrangement of each nozzle, such as whether the nozzles are arranged in a straight line, a matrix arrangement, or other specific layouts on the printing device, which is related to the planning of the nozzle coverage and printing sequence; count the number of nozzles of each nozzle, and the number of nozzles directly determines the amount of ink ejected per unit time and the printing resolution; master the ink color of each nozzle, so as to perform accurate color registration calculations later; at the same time, understand the geometric arrangement of each nozzle, such as whether the nozzles are evenly distributed on the nozzle surface or distributed according to a specific pattern, which has an important impact on the distribution of ink droplets on the curved surface and the color mixing effect. By comprehensively acquiring the printing information of these nozzles, sufficient basis is provided for the subsequent generation of accurate curved surface printing data based on the characteristics of the nozzles, ensuring the accurate presentation of colors and patterns during the printing process;

[0051] S5, based on step S3 and step S4, generating printing data of the corresponding surface from the original image by calculating the projection;

[0052] When generating print data, first read the surface mathematical model file from the storage module and extract the coordinate information of the polygonal surface vertices; then determine the relevant parameters of the nozzle motion plane (normal vector and constant term) according to the setting rules of the plane equation; then determine the print resolution of the original image (which can be obtained through the image file properties or print task settings). After that, for each vertex coordinate on the surface, calculate the point-to-plane distance and projection point coordinates in turn, and apply the projection point coordinate calculation method to all vertices. Finally, based on the printer-related information obtained (printing starting point, total number of passes, scanning range of each pass, etc.), a special data mapping algorithm is used to accurately map the original image pixel content to each nozzle hole at each pass position of the nozzle to generate a complete print data file, which is stored in the cache area that the printer can read;

[0053] S6, sending the printing data calculated in step S5 to the printer to start curved surface printing.

[0054] In step S6, the print data calculated in step S5 is accurately sent to the control system of the digital printer through the data transmission interface. After receiving these data, the control system of the printer drives the print head according to the corresponding motion trajectory, inkjet parameters and other requirements according to its internal preset printing logic and control algorithm, and performs point-by-point, line-by-line, and pass-by printing operations on the uneven curved surface. During the entire printing process, the print head accurately controls the inkjet timing, ink drop size and color of each nozzle according to the printing data, ensuring accurate color registration at all positions on the curved surface, and finally presenting a high-quality, expected printed image, completing the uneven curved surface printing task.

[0055] Preferably, step S1 is specifically to use laser scanning technology to scan the curved surface line by line using a laser beam, capture the reflected light signal through a high-precision optical signal receiving device, and accurately obtain the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information of the change in the intensity of the reflected light; or use structured light projection technology to project a preset specific light pattern onto the curved surface, and according to the deformation characteristics of the light pattern on the curved surface, use the principle of triangulation to carefully deduce the spatial position details of each point.

[0056] Preferably, the modeling accuracy of the mathematical model matches the printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the adjacent interval of printed pixels.

[0057] Preferably, the step S3 specifically includes, based on the driving of the print head of the printer itself, obtaining the printing track of printing on a flat surface when printing the curved surface image, determining the printing starting point, the total number of passes of the printed image, and the scanning range of each pass;

[0058] Preferably, the calculation projection method is as follows:

[0059] S51, obtaining vertex coordinates of the entire polygonal surface through a mathematical model, specifically including coordinates of all vertices on the surface;

[0060] S52, calculate the nozzle motion plane. In order to accurately describe the nozzle motion plane, the following plane equation form is used to express it. There are two planes, and their equations are recorded as follows:

[0061] Ax+By+Cz+D=0,

[0062] A′x+B′y+C′z+D′=0,

[0063] Where (A, B, C), (A′, B′, C′) are the normal vectors of the plane, and D and D′ are constant terms;

[0064] S53, obtaining the printing resolution of the original image;

[0065] S54, for any given point P (x, y, z) on the surface, the vertical distance d from point P to the plane can be calculated by the following formula:

[0066] d=∣Ax+By+Cz+D∣A2+B2+C2;

[0067] The calculation formula for the vertical distance d' from another point P'(x, y, z) on the surface to this plane is:

[0068] d′=A′2+B′2+C′2∣A′x+B′y+C′z+D′∣;

[0069] S55, the calculated distance dd' is moved from the point P(x,y,z)P'(x,y,z) on the surface to the plane by the distance dd' along the direction of the plane normal vector (A,B,C)(A',B',C'), and the projection point P is obtained. m (x m ,y m ,z m ) m ′(x m ,y m ,z m ). The direction of movement is the opposite of the vector (A, B, C)(A′, B′, C′), that is, (-A, -B, -C)(-A′, -B′, -C′). Therefore, the coordinate calculation formula of the projection point is:

[0070] x m =x+AA2+B2+C2·dx m =x+A2+B2+C2A·d;

[0071] y m =y+BA2+B2+C2·dy m =y+A2+B2+C2B·d;

[0072] z m =y+CA2+B2+C2·dz m =y+A2+B2+C2C·d;

[0073] S56, applying step S55 to all coordinate vertices obtained in step S51;

[0074] S57, according to the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle hole at each pass position of the nozzle to generate printing data.

[0075] Preferably, when performing curved surface printing in step S6, a high-definition camera is used to capture in real time the printing position of the nozzle on the curved surface, the ink droplet landing point, and the image of the printed part. Through image recognition and analysis technology, it is compared with the preset printing data. If deviations or abnormalities are found, printing is immediately paused, and printing parameters are adjusted according to the analysis results. Then printing is continued, thereby realizing real-time visual monitoring and dynamic adjustment of the curved surface printing process, ensuring that the printing task is completed smoothly and the quality meets the standards.

[0076] For example, a high-definition pattern is printed on a sculpture surface with concave and convex textures and irregular shapes. When printing on the raised part of the face, due to the large change in the curvature of the surface, in order to ensure that the ink droplets can accurately fall on the corresponding position and avoid the ink droplets splashing or deviating from the expected landing point due to the nozzle moving too fast, it is necessary to appropriately reduce the nozzle movement speed. Assuming that the nozzle movement speed in the relatively flat surface area is originally set to 50 mm per second, when printing on the raised bridge of the nose area on the face, the nozzle movement speed is reduced to 20 mm per second, so that the nozzle has more time to accurately spray ink droplets at the appropriate position, ensuring that the pattern can be clearly and accurately presented on the complex raised parts.

[0077] When printing on the concave areas of clothing wrinkles, the relative position relationship between the nozzle and the curved surface is complex and requires careful control of the ink droplet landing point. The speed must also be slowed down, possibly adjusted to 15 mm per second, to ensure that the ink droplets can be smoothly sprayed into the concave areas and evenly distributed, achieving high-quality printing effects.

[0078] On the contrary, when the nozzle moves to a relatively flat large area with small curvature change, such as the back of a sculpture, in order to improve printing efficiency, the nozzle movement speed can be appropriately increased, such as to 60 mm per second. In this way, the printing work of this area can be completed faster without affecting the printing quality.

[0079] In color curved surface printing, different colors of ink have different physical and chemical properties such as composition and viscosity, so the inkjet frequency needs to be adjusted accordingly. For example, when printing an advertising pattern containing a large number of red elements on a curved outdoor billboard, the viscosity of red ink may be slightly higher than that of other colors. In order to ensure that the red ink droplets can be ejected evenly and stably and accurately overlaid with other colors, it is necessary to appropriately reduce the inkjet frequency of the nozzle corresponding to the red ink.

[0080] Assume that the original inkjet frequency of the blue ink nozzle is 1000 pulses per second to trigger inkjet (this frequency can make the blue ink achieve better jetting effect under the current curved surface and printing environment), and the red ink has a viscosity problem, so the corresponding nozzle inkjet frequency is adjusted to 800 pulses per second to trigger inkjet, so that the size of the red ink droplets, the jetting speed, etc. can match the other colors, and finally achieve the effect of bright colors and accurate color registration for the entire advertising pattern.

[0081] Preferably, in step S53, when obtaining the printing resolution of the original image to be printed, when the original image has different resolutions on the surface, the image is segmented into areas with different resolutions, and then different mapping strategies are used to adapt the different areas to the surface, and finally the various parts are fused together through a fusion algorithm to generate printing data. This ensures the overall printing effect while making full use of various resolution information of the original image to improve the quality and layering of the printed image.

[0082] For example, on the curved surface of the shell of an electronic product, the shell surface has a certain curvature, and there are local function button areas, brand logo areas, and large-area texture decoration areas, etc., patterns are printed on it, and the image material includes high-resolution brand logos and low-resolution texture patterns.

[0083] The image is segmented, and the clear and exquisite brand logo, such as the text of the trademark, unique graphic symbols, etc., with a resolution of 600 pixels per inch, needs to accurately present its design details and color accuracy, and is segmented from the image as a high-resolution area. In the printing data generation stage, the high-precision printing capability of the nozzle is used for this part, and each pixel of the logo is mapped to the corresponding position of the shell surface through precise projection calculation. For example, the edge of the trademark text must be clear and sharp, and the color filling must be uniform, so the nozzle's inkjet angle, frequency, and movement speed and other parameters will be carefully adjusted according to the thickness and direction of the text strokes to ensure that each ink drop accurately constructs a high-quality logo effect.

[0084] For low-resolution texture patterns, such as some simple matte textures, which only need to reflect the general light and shadow effects and tactile style, with a resolution of about 100 pixels per inch, an adaptation method based on the overall characteristics of the texture is used. Texture is regarded as a set of pattern elements with a certain repetitive pattern and direction. According to the curvature and shape of the shell surface, it is mapped according to a larger unit area, so that the texture can be naturally spread on the surface. The nozzle can move and print in this area at a relatively fast speed, quickly covering a large area of ​​the texture area, while ensuring that the overall matte texture and light and shadow effects can be reflected.

[0085] The two are merged. After the brand logo and texture pattern are printed separately, the fusion operation is performed at their intersection. The color mixing algorithm is used to gradually change the ratio of ink drop colors within a transition area of ​​a certain width according to the color values ​​at the edge of the logo and the beginning of the texture, so that the logo and the texture can transition naturally, and it looks like an integrated design, which not only highlights the high definition and importance of the brand logo, but also shows the decorativeness of the texture pattern, and together creates a beautiful curved appearance printing effect that meets the product design requirements.

[0086] These examples show that the multi-resolution image adaptation and fusion solution can make full use of the resolution characteristics of different parts of the original image, combined with the surface morphology and printing requirements, to achieve high-quality, visually appealing surface printing color matching effects.

[0087] In this embodiment, the image segmentation algorithm includes a threshold segmentation algorithm, a segmentation algorithm based on region growing, or the edge detection segmentation algorithm.

[0088] In this embodiment, the threshold segmentation algorithm divides the image pixels into different categories according to the grayscale values ​​by setting one or more grayscale thresholds. For example, parts with obvious grayscale differences in high-resolution and low-resolution areas can be distinguished. This algorithm is suitable for simple situations in which the grayscale difference between the target and the background in the image is large.

[0089] In this embodiment, the segmentation algorithm based on region growing starts from some seed points in the image, continuously merges adjacent pixels according to certain similarity criteria (such as similarity of pixel grayscale, color, etc.), and gradually grows to form regions with similar features. It can be used to identify coherent high-resolution or low-resolution regions in the image, such as distinguishing between regions with similar feature continuity such as the human subject and background decoration in the art poster example.

[0090] In this embodiment, the edge detection segmentation algorithm uses edge information with drastic changes in pixel grayscale in the image to determine the boundaries of different areas. Common operators such as the Sobel operator and the Canny operator can detect the contours of objects in the image and assist in dividing different parts with high and low resolutions. It is often used in situations where different detailed areas of the image need to be accurately defined.

[0091] A curved surface printing color matching device comprises at least one processor, at least one memory and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the above-mentioned curved surface printing color matching method is implemented.

[0092] A storage medium stores computer program instructions, which implement the above-mentioned curved surface printing color matching method when the computer program instructions are executed by a processor.

[0093] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for printing color on a curved surface, characterized in that: The steps include: S1, collect surface data, measure the uneven surface to be printed through image recognition technology, and obtain the three-dimensional coordinate data of each point on the surface; S2, using mathematical modeling algorithms to construct a mathematical model that can accurately characterize the geometric characteristics of the surface; S3, obtaining information of the printing starting point of the digital printer, the total number of passes of the printed image, and the scanning range of each pass; S4, obtaining printing information of the print head through a digital printer, specifically including the number of print heads, the geometric arrangement of each print head, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle; S5, based on step S3 and step S4, generating printing data of the corresponding surface from the original image by calculating the projection; S6, sending the printing data calculated in step S5 to the printer to start curved surface printing.

2. A curved surface printing color registration method according to claim 1, characterized in that: Specifically, step S1 adopts laser scanning technology, uses a laser beam to scan line by line along the curved surface, captures the reflected light signal through a high-precision optical signal receiving device, and accurately obtains the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information of the change in the intensity of the reflected light.

3. A curved surface printing color registration method according to claim 1, characterized in that: The step S2 specifically comprises using a mathematical modeling algorithm to construct a mathematical model that can accurately characterize the geometric features of the surface through a method based on surface fitting or spline function.

4. A curved surface printing color registration method according to claim 3, characterized in that: The modeling accuracy of the mathematical model matches the printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the adjacent interval of printed pixels.

5. A curved surface printing color registration method according to claim 1, characterized in that: The step S3 specifically includes, based on the driving of the print head of the printer itself, obtaining the printing track of printing on the curved surface image as a flat surface, determining the printing starting point, the total number of passes of the printed image, and the scanning range of each pass.

6. A curved surface printing color registration method according to claim 1, characterized in that: The calculation projection method is as follows: S51, obtaining vertex coordinates of the entire polygonal surface through a mathematical model, specifically including coordinates of all vertices on the surface; S52, calculate the nozzle motion plane. In order to accurately describe the nozzle motion plane, the following plane equation form is used to express it. There are two planes, and their equations are recorded as follows: Ax+By+Cz+D=0, A′x+B′y+C′z+D′=0, Where (A, B, C), (A′, B′, C′) are the normal vectors of the plane, and D and D′ are constant terms; S53, obtaining the printing resolution of the original image; S54, for any given point P (x, y, z) on the surface, the vertical distance d from point P to the plane can be calculated by the following formula: d=∣Ax+By+Cz+D∣A2+B2+C2; The calculation formula for the vertical distance d' from another point P'(x, y, z) on the surface to this plane is: d′=A′2+B′2+C′2∣A′x+B′y+C′z+D′∣; S55, the calculated distance dd' is moved from the point P(x,y,z)P'(x,y,z) on the surface to the plane by the distance dd' along the direction of the plane normal vector (A,B,C)(A',B',C'), and the projection point P is obtained. m (x m ,y m ,z m ) m ′(x m ,y m ,z m ). The direction of movement is the opposite of the vector (A, B, C)(A′, B′, C′), that is, (-A, -B, -C)(-A′, -B′, -C′). Therefore, the coordinate calculation formula of the projection point is: x m =x+AA2+B2+C2·dx m =x+A2+B2+C2A·d; <h2 style=";text-align:left;direction:ltr">y<h2 style=";text-align:left;direction:ltr"> m <h2 style=";text-align:left;direction:ltr"> =y+BA2+B2+C2·dy<h2 style=";text-align:left;direction:ltr"> m <h2 style=";text-align:left;direction:ltr"> (y+A2+B2+C2B·d) <h2 style=";text-align:left;direction:ltr">z<h2 style=";text-align:left;direction:ltr"> m <h2 style=";text-align:left;direction:ltr"> =y+CA2+B2+C2·dz<h2 style=";text-align:left;direction:ltr"> m <h2 style=";text-align:left;direction:ltr"> (y+A2+B2+C2C·d) S56, applying step S55 to all coordinate vertices obtained in step S51; S57, according to the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle hole at each pass position of the nozzle to generate printing data.

7. A curved surface printing color matching device, characterized in that: The method comprises at least one processor, at least one memory and computer program instructions stored in the memory, and when the computer program instructions are executed by the processor, the method according to any one of claims 1 to 6 is implemented.

8. A storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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