A DLP projection method based on a chessboard pattern

Abstract

The present application relates to a kind of DLP projection methods based on chessboard mode, by processing the image generated after layering, the current layer image and the chessboard picture designed in advance are subjected to Boolean operation, obtain two black and white grid mutually exclusive projection images, finally project the two pictures by DLP light machine, the model finally obtained after projection is the image needed to print currently. By using the graphic processing method to the rest of the layer image, the image of each layer generates two pictures, and is projected and output. The parts printed by the chessboard projection mode solve the problems of large internal stress, poor surface quality of parts and other problems when printing large volume models, avoid the deformation of model printing, reduce the difficulty of model design and production, and improve the printing success rate.

Description

TECHNICAL FIELD

[0001] The application relates to the field of DLP three-dimensional printing technology, and particularly relates to a DLP projection method based on a chessboard mode. BACKGROUND

[0002] DLP 3D printing is a manufacturing technology for projecting and polymerizing ultraviolet light to materials, accumulating and printing parts through layer-by-layer solidification. The printing process comprises three-dimensional modeling, data layout slicing, printing picture file generation and model printing construction. The printing picture file is a picture generated from the contour line of the polygon form obtained through slicing, and is a key step in the whole model printing workflow. The existing DLP projection method is to directly project the printing picture, and when a part with a large printing area is printed, warping deformation occurs due to heat generated by material solidification, resulting in printing failure. In addition, when a dental model is printed, the printing area of the dental model bottom is large, and the printing area of the dental tip part is small, and the model precision after printing using the same parameters is poor. Based on this, the application designs a DLP projection method based on a chessboard mode to solve the above problems. SUMMARY

[0003] In view of the above problems, the application aims to provide a DLP projection method based on a chessboard mode.

[0004] The application provides the following technical scheme:

[0005] A DLP projection method based on a chessboard mode, the method comprising the following steps:

[0006] S1. importing a processed slice picture file,

[0007] S2. calculating a standard chessboard angle corresponding to the current layer according to the data imported in step S1, and generating a chessboard image with a corresponding size according to the device printing size;

[0008] S3. performing Boolean operation on the chessboard picture obtained in step S2 and the current layer image in the printing file, and generating a new picture according to the calculation result;

[0009] S4. calculating the remaining part image of the printing picture file according to the picture obtained in step 3; specifically, performing Boolean subtraction operation on the current layer printing picture file and the picture generated in step 3, and the remaining part after the subtraction is the new picture;

[0010] S5. performing printing exposure on the two pictures obtained in steps 3 and 4 respectively, and performing projection solidification on the picture in step 3 according to the process exposure time length requirement, and then performing the same operation on the picture in step 4 after the solidification of the picture in step 3 is completed;

[0011] S6. After projecting the current layer image, it is judged whether it is the last layer of printing picture data, if not, it returns to step 2 to continue the image processing of the subsequent layer, if yes, the printing and curing of the current part is completed;

[0012] S7. Finally, the data model actually needed to be printed is obtained.

[0013] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, the images introduced in the step S1 are all single-channel images, and the edges of the images have been processed by the anti-aliasing algorithm.

[0014] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, the standard chessboard pattern in the step S1 is determined according to the maximum area that can be projected by the printing device, and the chessboard pattern width is determined by the pixel resolution pix of the device multiplied by N pixels.

[0015] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, the standard chessboard pattern in the step S2 is generated in a 67° increment manner for each layer, and then the new chessboard pattern is used for the operation processing of the current layer image.

[0016] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, the number of pixels of the current image is calculated before the operation in the step S3, and if the number of pixels of the current layer image is less than the number of pixels of a chessboard pattern, the current layer image is directly used. Assuming that the size of the chessboard pattern is 100*100 pixels, and the size of the image is 80*80 pixels, the current image is projected in one chessboard pattern, and the calculated image projected in the chessboard pattern is still an 80*80 pixel image, which is the same as the current layer image. In order to save calculation, the previous layer image is directly used for projection printing. Assuming that the size of the chessboard pattern is 100*100 pixels, and the size of the image is 100*120 pixels, the current image is projected in two chessboard patterns, and the calculated image projected in the chessboard pattern is a 100*100 pixel image and a 100*20 pixel image, and then the two images projected in the chessboard pattern are used for the next Boolean operation.

[0017] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, a certain delay is needed in the step S5 when projecting the two images, and after the material is fully cured, the other generated image is projected.

[0018] As a preferred technical scheme of the DLP projection method based on the chessboard pattern, when the image of the remaining layer is processed in the step S6, the image of the previous layer is used for exposure printing, compared with the current layer and the previous layer, the direction and content of the two are consistent, in order to save the image processing time and improve the printing efficiency.

[0019] The beneficial effects of the present application are:

[0020] 1. The present application uses image processing technology to realize the operation and subtraction operation of image, through the segmentation and difference of image, the originally large area image is dispersed, in the subsequent printing process, the thermal stress generated during solidification is greatly reduced, the chessboard processed image also has a certain rotation angle between layers, so that the mechanical properties and dimensional accuracy of the part are also obviously improved than the traditional way, and when printing the part using the method of the present application, the model size and cross-sectional area of printing are not limited, and can be designed at will;

[0021] 2. The method in the present application can be used in any face exposure forming technology, only the standard chessboard size and the size and angle of the chessboard are modified, and the final desired result can be obtained by performing corresponding Boolean operation on the generated picture;

[0022] 3. The present application can also be used in the field of multi-light source DLP printing control, a plurality of chessboard pictures are used to perform corresponding Boolean operation on the original picture, divide the picture into several pictures, and the divided picture is used for curing corresponding light source, and the part size of the multi-light source DLP equipment is larger, the area of the corresponding pattern is also larger, the internal stress generated during part curing is also larger, and the size is also more difficult to control accurately, after using the method of the present application, the above problems can be effectively solved, the surface quality of the printed model is guaranteed, and the printing precision is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with embodiments of the present application, and do not constitute a limitation on the present application. In the drawings:

[0024] Figure 1 is a flowchart of the present application;

[0025] Figure 2 is a schematic diagram of the standard chessboard generated by the present application;

[0026] Figure 3 is a schematic diagram of the standard chessboard generated by the present application after rotating the angle;

[0027] Figure 4 is a schematic diagram of the present application importing a certain layer of slice picture after processing;

[0028] Figure 5 is a schematic diagram of the present application printing layer picture and generated standard chessboard operation;

[0029] Figure 6is a new picture schematic diagram obtained by subtracting the picture of the print layer from the picture of the standard checkerboard picture according to the present application;

[0030] Figure 7 is a new picture schematic diagram obtained by subtracting the picture of the print layer from the picture of the standard checkerboard picture according to the present application; Figure 6 DETAILED DESCRIPTION

[0031] The concept, specific structure and generated technical effects of the present application are described clearly and completely in combination with the embodiments and the drawings, so as to fully understand the purpose, scheme and effects of the present application. It should be noted that the embodiments and the features in the embodiments in the present application can be combined with each other without conflict. It should be noted that when a certain feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. In addition, the up, down, left, right and the like used in the present application are only relative to the relative position relationship of the components of the present application in the drawings.

[0032] Step 1: import a processed slice picture file, wherein the picture 4 of a certain layer is as shown in Figure 4

[0033] Step 2: according to the data imported in step 1, the standard checkerboard angle corresponding to the current layer is calculated; specifically, assuming that the current layer is n layer, the corresponding angle calculation method is a mod b=c, wherein a=n*67°, a is the actual angle to be rotated of the current layer, the size of b is 360°, and c is the standard checkerboard angle corresponding to the current layer;

[0034] The picture 2 as shown in Figure 2 is a checkerboard with an angle of 0°, and the checkerboard corresponding to the rotation angle angle Figure 3 The picture corresponding to the rotation angle angle as shown in Figure 3 is the standard checkerboard angle (that is, c) corresponding to the current layer, and then a corresponding size of the checkerboard image is generated according to the device printing size; the checkerboard is rotated once every 67 degrees, and the checkerboard can coincide once after 360 times, and the coincidence degree between the layers of the product printed out is the lowest, and the thermal stress between the layers during solidification can be offset;

[0035] Step 3: the Boolean operation is performed on the checkerboard picture obtained in step 2 and the file printed by the current layer Figure 4 (as shown in Figure 4 ); Figure 5 ​​As shown; in the print file picture, white is represented by gray scale 255, black is represented by gray scale 0, when the gray scale values of the print picture and the checkerboard are both 255, that is, the white parts of the two coincide, at this time the current area is retained; when the gray scale value of the print picture is 0, at this time no matter whether the checkerboard is black or white, it is displayed as black, when the print picture is the remaining gray scale value, at this time the gray scale value corresponding to the operation is obtained according to the gray scale value of the current position of the checkerboard, and finally the picture 6 (as shown in Figure 6 ) is obtained.

[0036] Step 4: calculate the remaining part of the print picture file image according to the picture 6 obtained in step 3; use the subtraction operation of the two pictures to subtract the current layer print picture file Figure 4 from the picture 6 generated in step 3, and the remaining part after the difference is obtained is the new picture 7 (as shown in Figure 7 );

[0037] Step 5: according to the two pictures obtained in step 3 and step 4 Figure 6 and Figure 7 , print exposure is performed on the two pictures respectively; according to the process exposure time requirement, first project and solidify the picture 6, and then perform the same operation on the picture 7 after the solidification of the picture 6 is completed.

[0038] Step 6: after projecting the current layer image, it is judged whether it is the last layer of print picture data, if not, return to step 2 to continue the image processing of the subsequent layer, if yes, the printing and solidification of the current part is completed.

[0039] The above only describes the preferred embodiments of the present application and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A DLP projection method based on a checkerboard pattern, characterized in that, The method includes the following steps: S1. Import a processed sliced ​​image file. S2. Based on the data imported in step S1, calculate the standard chessboard angle corresponding to the current layer, and generate a chessboard grid image of the corresponding size according to the printing size of the device; the standard chessboard grid in step S2 generates a new chessboard grid in increments of 67° per layer, and then performs calculations on the current layer image. S3. Based on the checkerboard image obtained in step S2, perform a Boolean operation with the current layer image in the print file, and generate a new image from the result. When the grayscale value of both the print image and the checkerboard is 255, that is, the white parts of the two overlap, the current area is retained. When the grayscale value of the print image is 0, the checkerboard will be displayed as black regardless of whether it is black or white. When the print image has other grayscale values, perform a bitwise AND operation based on the grayscale value of the current position of the checkerboard to obtain the corresponding grayscale value. S4. Calculate the remaining part of the printed image file based on the image obtained in step 3; specifically, use Boolean subtraction to subtract the image generated in step 3 from the current layer's printed image file, and the remaining part after the difference is the new image; S5. Based on the two images obtained in steps 3 and 4, print and expose these two images respectively. According to the process exposure time requirements, first perform image curing on the image in step 3. After the image in step 3 is cured, perform the same operation on the image in step 4. S6. After projecting the current layer image, determine whether it is the last layer of printed image data. If not, return to step 2 to continue image processing of subsequent layers. If so, complete the printing and curing of the current part. S7. Finally, we obtain the data model that is actually needed for printing.

2. The DLP projection method based on a checkerboard pattern according to claim 1, characterized in that: The images imported in step S1 are all single-channel images, and the image edges have been processed using an anti-aliasing algorithm.

3. The DLP projection method based on a checkerboard pattern according to claim 1, characterized in that: The standard checkerboard grid dimensions in step S1 are determined based on the maximum area that the printing device can project, and the checkerboard grid width is determined by multiplying the device's pixel resolution (pixels) by N pixels.

4. The DLP projection method based on a checkerboard pattern according to claim 1, characterized in that: In step S3, the number of pixels in the current image is calculated before the calculation. If the number of pixels in the current layer image is less than the number of pixels in one chessboard grid, the current layer image is used directly.

5. The DLP projection method based on a checkerboard pattern according to claim 1, characterized in that: In step S5, a certain delay needs to be added between the projections of the two images to allow the material to fully solidify before proceeding to the next step of projection and solidification.

6. The DLP projection method based on a checkerboard pattern according to claim 1, characterized in that: In step S6, when performing image processing on the remaining layers, the current layer is compared with the previous layer image. If the orientation and content of the two are consistent, the image generated by the previous layer is exposed and printed.

Images