A DLP multi-optical engine static projection splicing method and device

Abstract

This invention discloses a DLP multi-optical-engine static projection splicing device, comprising multiple sets of optical-engine mounting frames arranged in a ring. Each mounting frame includes a fixed bracket, a connecting frame, an XY motion platform, and reflectors. A rotary servo motor is mounted on the fixed bracket, and the connecting frame is rotatably mounted on the fixed bracket. The output shaft of the rotary servo motor is connected to the rotation shaft of the connecting frame. The XY motion platform is fixed on the connecting frame, and the projection axis of the optical engine is coaxial with the rotation axis of the connecting frame. The reflectors are located at the projection output end of the optical engine. The projection output of the optical engine is adjusted using the connecting frame and the XY motion platform, and the reflectors splice the projections of multiple optical engines onto the same projection surface. This effectively avoids the problem of large space occupation when directly using optical engines for projection, which requires considering the size of the optical engine itself, necessitating a projection surface larger than the optical engine itself for splicing. Utilizing multiple reflectors for reflective projection provides new possibilities for large-format, high-precision, multi-material DLP rapid prototyping.

Description

Technical Field

[0001] This invention belongs to the field of photopolymer additive manufacturing, specifically relating to a DLP multi-optical engine static projection splicing method and device. Background Technology

[0002] Photocuring refers to the curing process of monomer, oligomer, or polymer matrix under light induction. It is characterized by high efficiency, wide adaptability, economy, energy saving, and environmental protection. The activation energy generated by ultraviolet light, which has the highest energy in the spectrum, can break the C-C bonds of unsaturated polyester resin and generate free radicals, thereby curing the resin. When a photosensitizer is added to unsaturated polyester resin, ultraviolet or visible light can be used as the energy source to initiate the cross-linking reaction of the resin.

[0003] The two most common molding processes are SLA and DLP:

[0004] SLA (Stereolithography) is a commonly used resin-based 3D printing technology. The process involves slicing the model layer by layer, then selectively curing the two-dimensional cross-sections of each slice using a point-by-point ultraviolet laser, layer by layer, to create the final 3D model. Because SLA uses a point-by-point scanning method, its efficiency is affected by the size of the printing area, resulting in relatively low printing speed. However, SLA uses a small laser spot size of only 30µm, offering high precision and energy density. It can also form resin parts with low light absorption.

[0005] DLP (Digital Light Processing) is an imaging technology used in projectors and rear-projection televisions. In DLP projectors, the image is generated by a DMD (Digital Micromirror Device). A DMD consists of a matrix of micromirrors (precise, miniature reflectors) arranged on a semiconductor chip. Each micromirror controls a pixel in the projected image. The number of micromirrors corresponds to the resolution of the projected image. These micromirrors can rapidly change their angle under the control of digital drive signals. Once a corresponding signal is received, the micromirror tilts, thus changing the direction of reflection of the incident light. Mirrors in projection mode are shown as "open" and tilt with the digital signal, reflecting the incident light from the light source, which is then projected onto the working surface through a lens. Therefore, DLP can directly expose a two-dimensional cross-section of a model onto the working plane, and then obtain a three-dimensional model through layer-by-layer shaping.

[0006] Because DLP uses surface exposure, its forming efficiency is not affected by the size of the printing area, greatly improving printing efficiency. However, due to the limitation on the number of reflective mirrors in DMD, the larger the projection size, the worse the accuracy of individual mirrors (pixels) and the lower the energy density. Therefore, the projection area of ​​a single optical engine cannot be too large, which limits the size and materials of the parts that can be formed.

[0007] To overcome the limitations of a single optical engine's projected size on the printing process, multi-optical engine splicing is one of the currently available methods. However, this leads to the following problems:

[0008] 1. Taking the current highest precision 4K optical engine as an example, the optical engine itself is large in size. If multiple optical engines are spliced ​​together, the projection area must be at least larger than the size of the optical engine itself in order to achieve splicing of multiple optical engines. Not only is the precision of a single pixel large, but the energy density is also low, which limits the number and method of splicing optical engines.

[0009] 2. How to achieve accurate splicing of optical engine projections? Because the performance indicators of optical engines vary after they leave the factory, the focal lengths may not be exactly the same. Furthermore, processing errors during assembly or errors in the optical engine itself make it difficult to accurately align the projection surface size with the optical engine, making it impossible to directly use testing tools. How to measure the accuracy of the projection surfaces of different optical engines to ensure that the dimensions of the projection parts are consistent? Summary of the Invention

[0010] The purpose of this invention is to provide a DLP multi-optical engine static projection splicing method and apparatus to overcome the problem that existing technologies cannot ensure accuracy in multi-optical engine splicing.

[0011] A DLP multi-optical-engine static projection splicing device includes multiple optical engine mounting frames. Each mounting frame includes a fixed bracket, a connecting frame, an XY moving platform, and a reflector. The fixed bracket is fixed to one side of the optical platform used for optical shaping, and a rotation servo motor is mounted on the fixed bracket. The connecting frame is rotatably mounted on the fixed bracket, and the output shaft of the rotation servo motor is connected to the rotation shaft of the connecting frame. The XY moving platform is fixed on the connecting frame, and the optical engine used for optical projection is fixed on the XY moving platform. The projection axis of the optical engine is coaxial with the rotation axis of the connecting frame. The reflector is located at the projection output end of the optical engine and is set at an angle to the projection surface of the optical platform used for optical shaping. The multiple optical engine mounting frames are arranged in a ring, with the reflector located in the middle.

[0012] Preferably, a bearing is provided between the connecting frame and the fixed bracket, and a bearing hole is provided on the fixed bracket. The shaft of the connecting frame is fixed in the bearing hole of the fixed bracket through the bearing, and the output shaft of the rotating servo motor is fixedly connected to the shaft of the connecting frame.

[0013] Preferably, the XY moving platform includes an X sliding platform and a Y sliding platform. The Y sliding platform is fixed on the connecting frame, and the X sliding platform is disposed on the Y sliding platform. The X sliding platform can slide along the Y direction on the Y sliding platform. The optical engine is fixed on the X sliding platform and can slide along the X direction on the X sliding platform.

[0014] Preferably, the multiple reflectors are arranged at an angle to the projection surface of the optical platform used for optical shaping.

[0015] Preferably, the angle between the reflector and the projection surface of the optical platform used for optical shaping is 45°.

[0016] Preferably, multiple reflectors can be fixed on the same reflector fixing bracket, and the reflectors are fixed on the reflector fixing bracket by universal joints.

[0017] A DLP multi-optical engine static projection stitching method includes the following steps:

[0018] S1, using a reflector to adjust the projection images of at least two optical engines to be projected parallel onto the same projection plane;

[0019] S2, adjust the size of the projection images of each optical engine on the projection surface to be consistent;

[0020] S3. Using the projection image of one of the optical engines on the projection surface as a reference, adjust the projection images of the other optical engines in turn to be close to the reference projection image until the projection images of the optical engines are stitched together.

[0021] Preferably, the projection surface size of the optical engine is detected by optical measurement method, and then the position of each optical engine is adjusted to make the projection image size of each optical engine consistent.

[0022] Preferably, the projection spacing and offset angle of each optical engine within the correction reference map are measured using the correction reference map as a benchmark, and the optical engines are corrected based on the measurement results, so that the projection map size of each optical engine on the projection surface is consistent.

[0023] Preferably, the optical engine adjusts the focal length by moving in the X direction to correct the projection size of a single optical engine.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] This invention provides a DLP multi-optical-engine static projection splicing device, utilizing multiple optical engine mounting frames. Each mounting frame includes a fixed bracket, a connecting frame, an XY motion platform, and a reflector. The fixed bracket is fixed to one side of the optical platform used for optical shaping, and a rotation servo motor is mounted on the fixed bracket. The connecting frame is rotatably mounted on the fixed bracket, and the output shaft of the rotation servo motor is connected to the rotation shaft of the connecting frame. The XY motion platform is fixed to the connecting frame, and the optical engine used for optical projection is fixed to the XY motion platform. The projection axis of the optical engine is coaxial with the rotation axis of the connecting frame. The reflector is positioned on the projection axis of the optical engine. At the output end, the reflector is set at an angle to the projection surface of the optical platform used for optical forming. Multiple sets of optical engine mounting brackets are arranged in a ring, with the reflector located in the middle. The projection output of the optical engine is adjusted by using the connecting bracket and the XY moving platform. The projections of multiple optical engines are spliced ​​onto the same projection surface by using the reflector. This can effectively avoid the problem that direct projection by the optical engine occupies a large space and requires consideration of the size of the optical engine itself, which means that the projection surface must be larger than the size of the optical engine itself to achieve splicing. This application uses multiple reflectors for reflective projection, which provides new possibilities for large-format, high-precision, multi-material DLP rapid prototyping.

[0026] Preferably, this application utilizes a rotary servo motor to drive the connecting frame to rotate, and the axis of the optical engine is coaxial with the axis of the rotary servo motor, thereby ensuring that the projection emitted from the optical engine can rotate in place, thus achieving the purpose of the projection angle of the projected image on the projection surface. The structure is simple and easy to control. Furthermore, by using a reflector as the projection surface, the influence of the size of the optical engine itself on the projection can be avoided.

[0027] This invention discloses a DLP multi-optical engine static projection stitching method. It utilizes a reflector to adjust the projection images of at least two optical engines to be projected parallel onto the same projection plane. The projection image sizes of each optical engine on the projection plane are adjusted to be consistent, and stitching is performed by moving an XY platform. This method overcomes the problem of direct projection, where the projection plane must be larger than the optical engine itself for stitching to be possible, significantly improving projection accuracy and energy density. By employing lateral reflective projection and rotating the optical engines to correct the projection plane, it avoids the problems of image distortion and pixel overlap or gaps between adjacent optical engines after stitching. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the DLP multi-optical engine static projection splicing device in an embodiment of the present invention.

[0029] Figure 2 This is a top view of the DLP multi-optical engine static projection splicing device in an embodiment of the present invention.

[0030] Figure 3 This is a side view of the DLP multi-optical engine static projection splicing device in an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the optical-mechanical projection principle in an embodiment of the present invention.

[0032] Figure 5 This is an initial diagram of six optical-mechanical projections in an embodiment of the present invention.

[0033] Figure 6 This is a projection measurement diagram of a single optical engine in an embodiment of the present invention.

[0034] Figure 7 This is a schematic diagram of the structure used to correct the projection image using a reference object in an embodiment of the present invention.

[0035] Figure 8 This is a schematic diagram illustrating the principle of adjusting the focal length of the optical engine in an embodiment of the present invention.

[0036] Figure 9 This is a schematic diagram showing the consistent projection dimensions of the six optical engines in an embodiment of the present invention.

[0037] Figure 10 This is a schematic diagram of the distribution structure of the projection images of each optical engine after rotation in an embodiment of the present invention.

[0038] In the diagram, 1 is the rotating servo motor; 2 is the fixed bracket; 3 is the connecting frame; 4 is the optical engine; 5 is the X-sliding platform; 6 is the Y-sliding platform; and 7 is the reflector. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0041] like Figure 1 Paper Figure 4 As shown, this invention provides a DLP multi-optical-engine static projection splicing device, including multiple optical engine mounting frames. Each mounting frame includes a fixed bracket 2, a connecting frame 3, an XY moving platform, and a reflector 7. The fixed bracket 2 is fixed to one side of the optical platform used for optical shaping, and a rotation servo motor 1 is mounted on the fixed bracket 2. The connecting frame 3 is rotatably mounted on the fixed bracket 2, and the output shaft of the rotation servo motor 1 is connected to the rotation shaft of the connecting frame 3. The XY moving platform is fixed to the connecting frame 3, and the optical engine 4 used for optical projection is fixed to the XY moving platform. The projection axis of the optical engine 4 is coaxial with the rotation axis of the connecting frame 3. The reflector 7 is disposed on... At the projection output end of the optical engine 4, the reflector 7 is set at an angle to the projection surface of the optical platform used for optical forming. Multiple sets of optical engine mounting brackets are arranged in a ring, with the reflector 7 located in the middle. The projection output of the optical engine 4 is adjusted by the connecting bracket 3 and the XY moving platform. The projections of multiple optical engines 4 are spliced ​​onto the same projection surface by using the reflector 7. This can effectively avoid the problem that direct projection by the optical engine occupies a large space and requires consideration of the size of the optical engine itself, which means that the projection surface must be larger than the size of the optical engine itself to achieve splicing. This application uses multiple reflectors for reflective projection, which provides a new possibility for large-format, high-precision, multi-material DLP rapid prototyping.

[0042] This application utilizes a rotary servo motor 1 to drive the connecting frame 3 to rotate. The axis of the optical engine 4 is coaxial with the axis of the rotary servo motor 1, thereby ensuring that the projection emitted from the optical engine 4 can rotate in place, thus achieving the purpose of the projection angle of the projected image on the projection surface. The structure is simple and easy to control. Furthermore, by using a reflector 7 as the projection surface, the influence of the size of the optical engine 4 itself on the projection can be avoided.

[0043] A bearing is provided between the connecting frame 3 and the fixed bracket 2. The fixed bracket 2 is provided with a bearing hole. The shaft of the connecting frame 3 is fixed in the bearing hole of the fixed bracket 2 through the bearing. The output shaft of the rotating servo motor 1 is fixedly connected to the shaft of the connecting frame 3.

[0044] The XY moving platform includes an X sliding platform 5 and a Y sliding platform 6. The Y sliding platform 6 is fixed on the connecting frame 3, and the X sliding platform 5 is set on the Y sliding platform 6. The X sliding platform 5 can slide along the Y direction on the Y sliding platform 6. The optical engine 4 is fixed on the X sliding platform 5 and can slide along the X direction on the X sliding platform 5 (the direction of the line connecting the optical engine 4 and the reflector). Both the X sliding platform 5 and the Y sliding platform 6 are equipped with servo motors to realize rotation in the X and Y directions.

[0045] like Figure 4 As shown, multiple reflectors 7 are arranged at an angle to the projection surface of the optical platform used for optical forming. Specifically, the angle between the reflectors 7 and the projection surface of the optical platform used for optical forming is 45°.

[0046] Multiple reflectors 7 can be fixed on the same reflector fixing bracket. The reflectors 7 are fixed on the reflector fixing bracket by universal joints, and the angle of the reflectors 7 is adjustable.

[0047] In one embodiment of this application, the reflector 7 adopts a reflective lens structure, which is simple in structure and easy to install.

[0048] Based on the above-mentioned DLP multi-optical engine static projection splicing device, the present invention provides a DLP multi-optical engine static projection splicing method, comprising the following steps:

[0049] S1, using a reflector to adjust the projection images of at least two optical engines to be projected parallel onto the same projection plane;

[0050] S2, adjust the size of the projection images of each optical engine on the projection surface to be consistent;

[0051] S3. Using the projection image of one of the optical engines on the projection surface as a reference, adjust the projection images of the other optical engines in turn to be close to the reference projection image until the projection images of the optical engines are stitched together.

[0052] In this application, a DLP multi-optical-mechanical static projection splicing device is used to adjust the size (focal length), position, and angle of the optical-mechanical projection surface.

[0053] To ensure consistency in the projection dimensions of each optical engine on the projection surface, optical measurement methods are used to detect the projection surface dimensions of the optical engines. Then, the positions of each optical engine are adjusted to make the projection dimensions of each optical engine consistent.

[0054] Specifically, the steps include: using a correction reference image as a benchmark, measuring the projection spacing and offset angle of each optical engine within the correction reference image, and then using a DLP multi-optical engine static projection splicing device to correct the optical engines, thereby ensuring that the projection image size of each optical engine on the projection surface is consistent.

[0055] The optical engine adjusts the focal length by moving in the X direction to correct the projection size of a single optical engine, and uses a high-resolution camera to capture the projection image. Using a high-precision reference object of known size, the size of a pixel is calculated. The projection size of a single optical engine is calculated by the number of pixels, so that the projection size of each optical engine is consistent. Using the correction reference image as a reference, the projection surface is rotated by rotating the optical engine to make the two projection surfaces parallel.

[0056] Finally, by moving in the Y direction and moving in the X direction together with the reflector, one optical engine projection is used as a reference to move the other optical engine projection, thus completing the optical engine splicing.

[0057] Compared with direct projection, which involves moving and stitching via an XY platform, or correcting the projected image to complete the stitching, this invention overcomes the problem that direct projection requires the projection surface to be larger than the size of the optical engine itself for stitching to be possible, greatly improving the accuracy and energy density of the projection. By using lateral reflection projection and correcting the projection surface through a rotating optical engine, this invention avoids the problems of image distortion and pixel overlap or gaps between adjacent optical engine images after stitching is completed.

[0058] Example

[0059] The technical features of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0060] 1. Taking six optical engines as an example, let the optical engines be arranged in a rectangular pattern, such as... Figure 5 As shown, the original projection states of the six optical engines should be as follows: Figure 5 As shown, the parallel optical engines differ from each other by the distance of at least one optical engine in the Z direction;

[0061] 2. Determine the projection size of each optical engine based on the required dimensions, and perform optical measurements on each optical engine projection sequentially. To eliminate the influence of diffraction from large projection surfaces on the measurements, the following methods can be used: Figure 6 The image shown is used to perform projection measurements on 3x3 pixels at the four corners.

[0062] 3. Place a high-precision reference object of known size in each of the X and Y directions of the projection plane, and take pictures using a high-definition camera. The projected image and the reference objects should be in the same frame. The result is as follows. Figure 7 As shown;

[0063] 4. Extraction Figure 7 Given the pixel coordinates of the center points of two circular points of the reference object in the X and Y directions, and based on the Pythagorean theorem and the known dimensions, the size of a single pixel in the X and Y directions can be determined.

[0064] 5. Take the midpoint of the diagonal of the projected box in the diagram, and measure the distance between adjacent points respectively; if the projected size does not match the expectation, adjust the focal length of the optical engine by moving the X-axis of the optical engine platform to adjust the distance between the optical engine and the reflector, the principle of which is as follows. Figure 8 As shown;

[0065] 6. Repeat the above steps to adjust each optical engine individually, ensuring that the projection size of all six optical engines is consistent, and that all six optical engines emit light simultaneously. Project using the edge contour method and capture the image with a high-definition camera. The result is as follows. Figure 9 As shown;

[0066] 7. Using the captured image as a reference, and based on the coordinates of the extreme pixels of the projected contour, the offset angle of each projection plane relative to the captured image can be calculated using inverse trigonometric functions. The angles calculated by rotating each optical engine ensure parallelism between the projection planes. The results are as follows: Figure 10 As shown;

[0067] 8. Calculate the distances between the projection planes using the Pythagorean theorem. Preferably, using the projection image of one optical engine as a reference, the other five projection planes are translated in the XY direction by moving along the Y-axis and the Z-axis of the reflector. When translating in the X direction, the X-axis should also be moved simultaneously to ensure that the focal point of the optical engine does not change. Since the reflector angle is 45 degrees, the distance the optical engine moves is equal to the distance the reflector moves.

Claims

1. A DLP multi-optical engine static projection splicing device, characterized in that, The system includes multiple optical engine mounting frames, each comprising a fixed bracket (2), a connecting bracket (3), an XY moving platform, and a reflector (7). The fixed bracket (2) is fixed to one side of the optical platform used for optical forming, and a rotary servo motor (1) is mounted on the fixed bracket (2). The connecting bracket (3) is rotatably mounted on the fixed bracket (2), and the output shaft of the rotary servo motor (1) is connected to the rotation shaft of the connecting bracket (3). The XY moving platform is fixed on the connecting bracket (3), and the optical engine (4) used for optical projection is fixed on the XY moving platform. The projection axis of the optical engine (4) is coaxial with the rotation axis of the connecting bracket (3). The reflector (7) is located at the projection output end of the optical engine (4), and the reflector (7) is angled to the projection surface of the optical platform used for optical forming. The multiple optical engine mounting frames are arranged in a ring, with the reflector (7) located at... In the middle, a bearing is provided between the connecting frame (3) and the fixed bracket (2). The fixed bracket (2) is provided with a bearing hole. The shaft of the connecting frame (3) is fixed in the bearing hole of the fixed bracket (2) through the bearing. The output shaft of the rotating servo motor (1) is fixedly connected to the shaft of the connecting frame (3). The XY moving platform includes an X sliding platform (5) and a Y sliding platform (6). The Y sliding platform (6) is fixed on the connecting frame (3). The X sliding platform (5) is set on the Y sliding platform (6). The X sliding platform (5) can slide along the Y direction on the Y sliding platform (6). The optical engine (4) is fixed on the X sliding platform (5). The optical engine (4) can slide along the X direction on the X sliding platform (5). The angle between the reflector (7) and the projection surface of the optical platform used for optical forming is 45°. The moving distance of the optical engine is equal to the moving distance of the reflector.

2. The DLP multi-optical engine static projection splicing device according to claim 1, characterized in that, Multiple reflectors (7) are set at an angle to the projection surface of the optical platform used for optical forming.

3. The DLP multi-optical engine static projection splicing device according to claim 2, characterized in that, Multiple reflectors (7) can be fixed on the same reflector fixing bracket. The reflectors (7) are fixed on the reflector fixing bracket by universal joints.

4. A DLP multi-optical engine static projection splicing method based on the DLP multi-optical engine static projection splicing device of claim 1, comprising the following steps: S1, using a reflector to adjust the projection images of at least two optical engines to be projected parallel to the same projection plane; S2, adjust the size of the projection images of each optical engine on the projection surface to be consistent; S3. Using the projection image of one of the optical engines on the projection surface as a reference, adjust the projection images of the other optical engines in turn to be close to the reference projection image until the projection images of all optical engines are stitched together.

5. A DLP multi-optical engine static projection stitching method according to claim 4, characterized in that, The projection surface size of the optical engine is measured using optical measurement methods, and then the position of each optical engine is adjusted to make the projection image size of each optical engine consistent.

6. The DLP multi-optical engine static projection stitching method according to claim 4, characterized in that, Using a correction reference image as a benchmark, the projection spacing and offset angle of each optical engine within the correction reference image are measured. Based on the measurement results, the optical engines are corrected so that the projection image size of each optical engine on the projection surface is consistent.

7. A DLP multi-optical engine static projection stitching method according to claim 4, characterized in that, The optical engine adjusts the focal length by moving in the X direction to correct the projection size of a single optical engine.

Images