Position and velocity based 3D printing synchronized exposure system and method

Abstract

The application provides a position and speed based 3D printing synchronous exposure system and method, comprising a light source, a light source switch, a light source movement system, a light source exposure duration timer and a light source image refresh control system; the light source comprises a plurality of sub light sources arranged side by side along the y-axis direction; the light source movement system is used for driving the light source to move at a constant speed along the x-axis direction; and the light source image refresh control system is used for controlling the time when each sub light source starts to refresh the image of the corresponding pixel point. The application adopts a method combining machine movement and light source image refresh, controls the light source to perform single continuous push scanning exposure on a super large image, and can greatly improve the finished product efficiency of the printing workpiece. The application uses a method combining the control of machine movement speed and light source image refresh, so that the exposure effects of each part of the image are consistent, and similarly, the curing effects of each part of the exposure surface are also consistent, and therefore the performances of the final printing finished product are greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 3D printing, and particularly relates to a 3D printing synchronous exposure system and method based on position and speed. BACKGROUND

[0002] The light source projection is very important in the light-curing forming technology in the additive 3D printing manufacturing technology. In the actual additive manufacturing process, the accuracy of the light source projection image, the size of the light source projection range and the length of the light source projection time have important influences on the forming effect and forming efficiency of the printed workpiece.

[0003] The existing light-curing forming technology needs to cut a large image of the same layer into several small images when facing a workpiece with an ultra-large volume, and then moves the light source to the positions corresponding to the small images respectively, stops the movement of the light source at the corresponding positions and performs continuous projection, so as to realize the projection of each small image. After the projection of the several small images is completed, a complete single-layer image is obtained.

[0004] This 3D printing exposure method has the problems of low forming efficiency and low forming precision, and cannot meet the forming requirements of the workpiece with an ultra-large volume at present. SUMMARY

[0005] In view of the defects of the prior art, the application provides a 3D printing synchronous exposure system and method based on position and speed, which can effectively solve the above problems.

[0006] The technical scheme adopted by the application is as follows:

[0007] The application provides a 3D printing synchronous exposure system based on position and speed, which comprises a light source, a light source switch, a light source movement system, a light source exposure duration timer and a light source image refreshing control system.

[0008] The light source comprises a plurality of rows of sub-light source groups, and each row of sub-light source groups comprises a plurality of sub-light sources arranged side by side along the y-axis direction.

[0009] The light source switch is used for uniformly controlling the on-off of each row of sub-light source groups.

[0010] The light source movement system is used for driving the light source to move uniformly along the x-axis direction.

[0011] The light source exposure duration timer is used for starting timing when each row of sub-light source groups is turned on uniformly for exposure, and simultaneously turning off each row of sub-light source groups when the timing length T is reached, to end the exposure.

[0012] The light source image refreshing control system is used for controlling the time when each row of sub-light source groups starts to refresh the image of the corresponding pixel point.

[0013] Preferably, the light source image refresh control system comprises an image refresh controller, an x-axis direction displacement sensor, a first pulse receiving unit, a pulse sending unit and a second pulse receiving unit.

[0014] The x-axis direction displacement sensor is used for detecting the displacement of the light source moving at a constant speed along the x-axis direction, and the output end of the x-axis direction displacement sensor is connected with the first pulse receiving unit; the output end of the first pulse receiving unit is connected with the image refresh controller; the output end of the image refresh controller is connected with the second pulse receiving unit; and the output end of the second pulse receiving unit is connected with the light source.

[0015] The application further provides a method of a 3D printing synchronous exposure system based on position and speed, comprising the following steps:

[0016] Step 1, for an image projection area needing 3D printing, a plane rectangular coordinate system xy is established with the upper left corner of the image projection area as a coordinate origin, wherein the x direction is a push scanning direction and the y direction is a transverse direction;

[0017] The image needing 3D printing has a size of c*d, c is the number of pixel points in the x direction, and d is the number of pixel points in the y direction, so the image has c rows and d columns of pixel points.

[0018] Step 2, a 3D printing synchronous exposure system based on position and speed is built, wherein the light source comprises a row of sub light source groups, each group of sub light source groups comprises b sub light sources arranged side by side along the y-axis direction, and a light source movement system makes the a row of sub light source groups pass above the image projection area; and a is less than c and b is less than d.

[0019] For the image needing 3D printing, the image is divided into multiple image projection sub-areas along the y direction, and the light source is controlled to perform 3D printing synchronous exposure on each image projection sub-area in sequence.

[0020] For any image projection sub-area, the following method is used to control the light source to perform 3D printing synchronous exposure on the area:

[0021] Step 2.1, initially, the light source is at a position outside the image projection area, moves at an acceleration along the x direction, reaches a target speed before the position x=0 of the image projection sub-area, and then moves at the target speed and passes through the image projection area.

[0022] Firstly, b sub-sources of the first row sub-source group pass through the position of x=0 of the image projection sub-region, i.e., the first-1 sub-source, the first-2 sub-source, …, the first-b sub-source, and reach the starting positions of the first row first column pixel point, the first row second column pixel point, …, the first row bth column pixel point of the image projection sub-region, respectively;

[0023] Step 2.2, controlling the light source to move at a constant speed along the x direction from the position of x=0 above the image projection sub-region through the light source movement system;

[0024] From t=0, during the process of the light source moving at a constant speed, whenever b sub-sources of the arbitrary kth row sub-source group move to the starting position of the ith row pixel point of the image projection sub-region, k=1, 2, …, a, i=1, 2, …, c, control b sub-sources of the kth row sub-source group to refresh the pixel point images of the corresponding pixel point positions at the same time, and simultaneously turn on b sub-sources of the kth row sub-source group through the light source switch to make b sub-sources of the kth row sub-source group start exposure at the same time;

[0025] Among them, controlling b sub-sources of the kth row sub-source group to refresh the pixel point images of the corresponding pixel point positions, specifically: for the k-1th sub-source, the k-2th sub-source, …, the k-bth sub-source, refresh the pixel point images of the ith row first column pixel point, the ith row second column pixel point, …, the ith row bth column pixel point of the image projection sub-region, respectively;

[0026] From the start of exposure of b sub-sources of the kth row sub-source group, the light source exposure duration timer starts timing, when the continuous exposure time reaches the timing length T, wherein the timing length T is set, at this time b sub-sources of the kth row sub-source group are still moving in the ith row pixel point, and b sub-sources of the kth row sub-source group are simultaneously turned off through the light source switch to make b sub-sources of the kth row sub-source group end exposure at the same time;

[0027] After b sub-sources of the kth row sub-source group end exposure at the same time, when they move at a constant speed to the starting position of the next row pixel point, b sub-sources of the kth row sub-source group refresh the pixel point images again at the same time and start exposure; after the continuous exposure time, i.e., the timing length T, b sub-sources of the kth row sub-source group are turned off at the same time to make b sub-sources of the kth row sub-source group end exposure at the same time; thus, the process of moving at a constant speed along the x direction is repeated to complete the complete exposure of the image projection sub-region in pixel point units.

[0028] Preferably, step 2.2 is specifically:

[0029] Step 2.2.1, assuming that the actual physical length of a single pixel point along the x direction is d microns; the coefficient of the x-axis direction displacement sensor is f, that is, the number of pulses generated by the displacement sensor per 1 micron of movement is 1 / f; the movement speed of the light source along the x direction is v pulses per millisecond;

[0030] Step 2.2.2, in the process of uniform motion of the b sub-sources in the kth row of sub-source groups, the x-axis direction displacement sensor detects the displacement of the b sub-sources in the kth row of sub-source groups, and generates pulses at a certain frequency according to the coefficient f, and the generated pulses are sent to the first pulse receiving unit in real time; the first pulse receiving unit feeds back the received pulses to the image refresh controller;

[0031] From t=0, the image refresh controller counts the number of pulses received from the first pulse receiving unit, and every time d / f pulses are received, it means that the b sub-sources in the kth row of sub-source groups have moved to the starting position of a certain column of pixel points, therefore, the image refresh controller controls the pulse sending unit to send a pulse to the second pulse receiving unit, and every time the second pulse receiving unit receives a pulse, it triggers the b sub-sources in the kth row of sub-source groups to perform pixel point image refresh and sub-source opening actions;

[0032] Every time the b sub-sources in the kth row of sub-source groups perform pixel point image refresh and sub-source opening actions, the light source exposure duration timer is started, and when the timing time length T is reached, the b sub-sources in the kth row of sub-source groups are closed at the same time.

[0033] Preferably, the maximum value of the timing time length T is the maximum continuous exposure time t of the sub-source max , which satisfies the following inequality:

[0034] t max <d / (v*f).

[0035] The 3D printing synchronous exposure system and method based on position and speed provided by the application have the following advantages:

[0036] 1. The application adopts a method of combining machine movement and light source image refresh to control the light source to perform single continuous push-scan exposure on a super large image, which can greatly improve the finished product efficiency of the printed workpiece.

[0037] 2. The application uses a method of combining control of machine movement speed and light source image refresh to make the exposure effects of different parts of the image consistent, and similarly, the curing effects of different parts of the exposure surface are also consistent, thereby greatly improving the performance of the final printed product. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1The structural connection schematic diagram of the position and speed based 3D printing synchronous exposure system provided by the present application is shown in the figure;

[0039] Figure 2 The principle diagram of the position and speed based 3D printing synchronous exposure method provided by the present application is shown in the figure.

[0040] Figure 3 The embodiment diagram of the position and speed based 3D printing synchronous exposure method provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0042] In the traditional scheme, the projection mode of a super large image is divided into three steps: first, the super large image is cut to obtain a plurality of sub-images matched with the size of the light source; then the machine moves the light source to the specified position corresponding to each sub-image and stops moving; finally, the light source projects the sub-image corresponding to the specified position and lasts for a period of time, realizing the light curing forming of the specified position. When each sub-image is projected, the projection of the super large image is completed. Therefore, when the image is larger, the number of sub-images after cutting is larger, and finally more machine movements and stops and waiting for the projection time to end are required. In this process, errors may occur in the projection position of the light source due to the movement precision of the machine, which will continuously accumulate and cause the precision of the finally manufactured workpiece to not meet the requirements, or even the manufacturing to fail. Secondly, too much machine movement and light source projection occupies a lot of time, reducing the manufacturing efficiency of the super large workpiece.

[0043] In order to solve the problems of low forming efficiency and low forming precision caused by the step-by-step execution of mechanical movement and light source projection in the traditional light curing forming technology, the present application connects the light source projection and mechanical movement through the cooperation of the control module and the light source module, realizes the position and speed based 3D printing synchronous push-scan exposure control of the light source, and in the process of uniform motion of the light source, the continuous high-precision continuous exposure of the super large image can be completed without stopping the movement of the light source, which can effectively improve the forming efficiency and forming precision, and the performance of the printed workpiece is also greatly improved.

[0044] REFERENCE Figure 1 The position and speed based 3D printing synchronous exposure system provided by the present application comprises a light source, a light source switch, a light source movement system, a light source exposure duration timer and a light source image refresh control system.

[0045] The light source comprises a plurality of rows of sub-light source groups, each row of sub-light source groups comprising a plurality of sub-light sources arranged side by side along the y-axis direction;

[0046] The light source switch is used for unified control of turning on and off of each row of the sub-light source groups;

[0047] The light source movement system is used for driving the light source to move at a uniform speed along the x-axis direction;

[0048] The light source exposure duration timer is used for starting timing of exposure of each row of the sub-light source groups each time when they are turned on simultaneously, and closing each row of the sub-light source groups when the timing time length T is reached, thereby ending the current exposure;

[0049] The light source image refresh control system is used for controlling a time when each row of the sub-light source groups starts to refresh an image of a corresponding pixel point.

[0050] As a specific implementation, the light source image refresh control system comprises an image refresh controller, an x-axis direction displacement sensor, a first pulse receiving unit, a pulse sending unit and a second pulse receiving unit;

[0051] The x-axis direction displacement sensor is used for detecting displacement of the light source moving at a uniform speed along the x-axis direction, an output end of the x-axis direction displacement sensor is connected with the first pulse receiving unit; an output end of the first pulse receiving unit is connected with the image refresh controller; an output end of the image refresh controller is connected with the second pulse receiving unit; and an output end of the second pulse receiving unit is connected with the light source.

[0052] Reference Figure 2 The application further provides a method of a 3D printing synchronous exposure system based on position and speed, comprising the following steps:

[0053] Step 1, for an image projection area needing 3D printing, a plane rectangular coordinate system xy is established with the upper left corner of the image projection area as a coordinate origin, wherein the x direction is a push scanning direction and the y direction is a transverse direction;

[0054] The image needing 3D printing has a size of c*d, c is a number of pixel points in the x direction, and d is a number of pixel points in the y direction, so the image has c rows and d columns of pixel points;

[0055] Step 2, a 3D printing synchronous exposure system based on position and speed is built, wherein the light source comprises a rows of sub-light source groups, each group of the sub-light source groups comprises b sub-light sources arranged side by side along the y-axis direction, a light source movement system drives the a rows of sub-light source groups to pass above the image projection area; and a is less than c and b is less than d;

[0056] For the image needing 3D printing, the image is divided into multiple image projection sub-areas along the y direction, and the light source is controlled to perform 3D printing synchronous exposure on each image projection sub-area in sequence.

[0057] For any one image projection sub-region, the following method is used to control the light source to perform synchronous exposure with 3D printing in the region:

[0058] Step 2.1, initially, the light source moves at an acceleration outside the image projection area along the x direction, reaches the target speed before the position of x = 0 of the image projection sub-region, and then moves at a constant speed using the target speed and passes through the image projection area;

[0059] First, the b sub-light sources of the first row of sub-light source groups pass through the position of x = 0 of the image projection sub-region, that is, the first-1 sub-light source, the first-2 sub-light source, …, the first-b sub-light source, respectively reach the starting positions of the first row, the first column pixel point, the first row, the second column pixel point, …, the first row, the bth column pixel point of the image projection sub-region;

[0060] Step 2.2, control the light source to move at a constant speed in the x direction above the image projection sub-region from the position of x = 0 through the light source movement system;

[0061] From t = 0, during the constant speed movement of the light source, every time the b sub-light sources of any kth row of sub-light source groups move to the starting position of the ith row of pixel points of the image projection sub-region, where k = 1, 2, …, a, i = 1, 2, …, c, control the b sub-light sources of the kth row of sub-light source groups to refresh the pixel point images of the corresponding pixel point positions at the same time, and simultaneously turn on the b sub-light sources of the kth row of sub-light source groups through the light source switch, so that the b sub-light sources of the kth row of sub-light source groups start exposure at the same time;

[0062] Wherein, the b sub-light sources of the kth row of sub-light source groups are controlled to refresh the pixel point images of the corresponding pixel point positions, specifically: for the k-1th sub-light source, the k-2th sub-light source, …, the k-bth sub-light source, refresh the pixel point images of the first column pixel point, the second column pixel point, …, the bth column pixel point of the ith row of the image projection sub-region;

[0063] From the start of exposure of the b sub-light sources of the kth row of sub-light source groups, the light source exposure duration timer starts timing, when the continuous exposure time reaches the timing length T, wherein the timing length T is set, at this time the b sub-light sources of the kth row of sub-light source groups are still moving in the ith row of pixel points, and the b sub-light sources of the kth row of sub-light source groups are simultaneously turned off through the light source switch, so that the b sub-light sources of the kth row of sub-light source groups end exposure at the same time;

[0064] After the b sub-sources of the kth row of sub-source groups end exposure at the same time, when they move to the starting position of the next row of pixel points at a constant speed, the b sub-sources of the kth row of sub-source groups refresh the pixel point image at the same time again and start exposure; after a continuous exposure time, i.e. a timing length T, the b sub-sources of the kth row of sub-source groups are closed at the same time, so that the b sub-sources of the kth row of sub-source groups end exposure at the same time; the process is repeated to complete the complete exposure of the image projection sub-region in units of pixel points in the process of moving at a constant speed along the x direction.

[0065] As a specific implementation, step 2.2 is specifically:

[0066] Step 2.2.1, assuming that the actual physical length of a single pixel point along the x direction is d microns; the coefficient of the x-axis direction displacement sensor is f, i.e. the number of pulses generated by the displacement sensor per 1 micron of movement is 1 / f; the movement speed of the light source moving at a constant speed along the x direction is v pulses per millisecond;

[0067] Step 2.2.2, in the process of the b sub-sources of the kth row of sub-source groups moving at a constant speed, the x-axis direction displacement sensor detects the displacement of the b sub-sources of the kth row of sub-source groups and generates pulses at a certain frequency according to the coefficient f, and the generated pulses are sent to the first pulse receiving unit in real time; the first pulse receiving unit feeds back the received pulses to the image refresh controller;

[0068] Starting from t=0, the image refresh controller counts the number of pulses received from the first pulse receiving unit, and every time d / f pulses are received, it means that the b sub-sources of the kth row of sub-source groups move to the starting position of a column of pixel points, therefore, the image refresh controller controls the pulse sending unit to send a pulse to the second pulse receiving unit every time the second pulse receiving unit receives a pulse, triggering the b sub-sources of the kth row of sub-source groups to perform pixel point image refresh and sub-source opening actions;

[0069] Every time the b sub-sources of the kth row of sub-source groups perform pixel point image refresh and sub-source opening actions, the light source exposure duration timer is started, and when the timing length T is reached, the b sub-sources of the kth row of sub-source groups are closed at the same time.

[0070] Wherein, the maximum value of the timing length T is the maximum continuous exposure time t of the sub-source max , satisfies the following inequality:

[0071] t max <d / (v*f).

[0072] Specifically, according to the light-on and light-off diagram of a single pixel point in the light source push-scan process, it can be seen that the exposure of a single pixel point is realized while the machine is moving, for example, when a certain row of sub-light source groups moves to the starting position t0 of a certain row of pixel points, the sub-light sources of the row immediately expose, and as the machine moves, the sub-light sources that are still exposing will inevitably affect the projection of the next row of pixel points, thus it can be seen that the uniformity of the exposure effect of the light source at each position ultimately depends on whether the continuous exposure time of the light source after each image refresh is consistent. The continuous exposure time of the light source can be set according to the actual situation, that is, the value of the timing length T. The controllable range of the continuous exposure time of the light source is from the limit refresh interval of the light source itself to the time obtained by dividing the length of a single pixel point by the moving speed of the light source, that is, the maximum continuous exposure time t max of the light source. Based on the parameters of the image refresh signal, the moving speed of the light source is v pulses / millisecond, and the time left for the light source to close the exposure. At this time, the maximum continuous exposure time t max of the light source should be less than d / (v*f). As can be seen from the continuous exposure time formula, d represents the actual physical length of a single pixel point in the x direction, and f represents the coefficient of the x-axis direction displacement sensor, both of which are quantitative. Therefore, as long as the moving speed of the light source, that is, the speed of the machine in the push-scan direction, is unchanged, the continuous exposure time is unchanged. According to the relationship between speed and time, at this time, the moving position of the light source driven by the machine is also consistent, that is, from the beginning of the exposure to the end of the exposure, the position of the current pixel point entering the next row of pixel points is consistent. In this way, until the single image push-scan is completed, all pixel points are affected consistently, and finally the consistency of the exposure effect of each part of the projection area can be ensured.

[0073] For the convenience of understanding the present application, as shown in Figure 3 , it is a schematic diagram of the principle of the 3D printing synchronous exposure method based on position and speed. As can be seen from Figure 3 , for a large image projection area, every 6 columns of pixel points form an image projection sub-area. The light source scans each image projection sub-area in turn. Of course, 6 columns here are only a reference example, and in actual application, 1920 columns are usually taken as an image projection sub-area.

[0074] For the light source, a total of 3 rows of sub-light source groups are included, and taking the scanning and exposure of the 1st image projection sub-area as an example:

[0075] When the 6 sub-light sources of the 1st row of sub-light source groups reach the starting position of the 1st row of pixel points of the 1st image projection sub-area, that is, the upper boundary of the 1st row of pixel points, the 6 sub-light sources of the 1st row of sub-light source groups are controlled to refresh the pixel point image of the corresponding pixel point position at the same time, and at the same time, the light source switch is turned on to open the 6 sub-light sources of the 1st row of sub-light source groups, and the exposure is started. After a timing length T, the 6 sub-light sources of the 1st row of sub-light source groups are turned off at the same time, and the exposure of the pixel points of the 1st row is ended;

[0076] Then, when the 6 sub-light sources of the 1st row sub-light source group reach the starting position of the 2nd row of pixel points of the 1st image projection sub-region, i.e. the upper boundary of the 2nd row of pixel points, the 6 sub-light sources of the 1st row sub-light source group are controlled to refresh the pixel point images of the corresponding pixel point positions at the same time, and the light source switch is used to open the 6 sub-light sources of the 1st row sub-light source group at the same time to start exposure, and after a timing time length T, the 6 sub-light sources of the 1st row sub-light source group are closed at the same time to end the exposure of the pixel points in the 2nd row; by analogy, the 6 sub-light sources of the 1st row sub-light source group complete the exposure of the pixel points in each row during uniform motion.

[0077] Similarly, when the 6 sub-light sources of the 2nd row sub-light source group reach the starting position of the 1st row of pixel points of the 1st image projection sub-region, i.e. the upper boundary of the 1st row of pixel points, the 6 sub-light sources of the 2nd row sub-light source group are controlled to refresh the pixel point images of the corresponding pixel point positions at the same time, and the light source switch is used to open the 6 sub-light sources of the 2nd row sub-light source group at the same time to start exposure, and after a timing time length T, the 6 sub-light sources of the 2nd row sub-light source group are closed at the same time to end the exposure of the pixel points in the 1st row; by analogy, the 6 sub-light sources of the 2nd row sub-light source group complete the exposure of the pixel points in each row during uniform motion.

[0078] Similarly, when the 6 sub-light sources of the 3rd row sub-light source group reach the starting position of the 1st row of pixel points of the 1st image projection sub-region, i.e. the upper boundary of the 1st row of pixel points, the 6 sub-light sources of the 3rd row sub-light source group are controlled to refresh the pixel point images of the corresponding pixel point positions at the same time, and the light source switch is used to open the 6 sub-light sources of the 3rd row sub-light source group at the same time to start exposure, and after a timing time length T, the 6 sub-light sources of the 3rd row sub-light source group are closed at the same time to end the exposure of the pixel points in the 1st row; by analogy, the 6 sub-light sources of the 3rd row sub-light source group complete the exposure of the pixel points in each row during uniform motion.

[0079] Therefore, if the light source is provided with 3 rows of sub-light source groups, the pixel points in each row pass through 3 times of push scanning exposure during the process of completing the push scanning exposure of the image projection sub-region once, which can improve the push scanning exposure effect.

[0080] It should be emphasized that Figure 3 The number of rows of sub-light source groups and the number of sub-light sources in each row of sub-light source groups in the light source are only examples and are not used to limit the present application. The number of rows of sub-light sources and the number of sub-light sources in each row of sub-light sources can be flexibly set according to requirements.

[0081] The 3D printing synchronous exposure system and method based on position and speed provided by the present application have the following characteristics:

[0082] 1、The present application adopts the method of combining machine motion with light source image refreshing, controls the light source to perform single continuous push scanning exposure on the super large image, and can greatly improve the workpiece product printing efficiency.

[0083] 2、The present application uses the method of combining the control of machine motion speed with light source image refreshing, makes the exposure effect of each part of the image consistent, and the curing effect of each part of the exposure surface is also consistent, so the performance of the final printed product is greatly improved.

[0084] The present application provides a 3D printing synchronous exposure system based on position and speed, through hardware connection and software control, the light source can project the corresponding image according to the position feedback of machine motion, and at the same time, the projection time length of the light source in the same position is ensured by controlling the machine motion speed. The method is that the machine is in the continuous motion process in a single direction, the projection image is refreshed according to the actual position in pixel units, not only greatly reduces the precision problem caused by multiple start and stop, but also can improve the manufacturing efficiency of the workpiece, at the same time, the control of the uniform motion of the machine can ensure that the projection surface receives the projection time length of the light source, so that the curing effect of each part is consistent, and the performance of the final printed product is greatly improved.

[0085] The above is only the preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method of employing a location and velocity based 3D printing simultaneous exposure system, characterized by, The position and speed based 3D printing synchronous exposure system comprises a light source, a light source switch, a light source movement system, a light source exposure duration timer and a light source image refresh control system; The light source comprises a plurality of rows of sub-light source groups, each row of sub-light source groups comprising a plurality of sub-light sources arranged side by side along the y-axis direction; The light source switch is configured to uniformly control the on-off of each row of the sub-light source groups; The light source movement system is configured to drive the light source to move at a constant speed along the x-axis direction; The light source exposure duration timer is configured to start timing when each row of the sub-light source groups is turned on uniformly for exposure, and simultaneously turn off each row of the sub-light source groups when the timing reaches a timing length T, thereby ending the current exposure; The light source image refresh control system is configured to control the time when each row of the sub-light source groups starts to refresh the image of the corresponding pixel point; The method comprises the following steps: Step 1: For an image projection area that needs to be 3D printed, a plane rectangular coordinate system xy is established with the upper left corner of the image projection area as the coordinate origin, wherein the x direction is the push scanning direction and the y direction is the transverse direction; The image that needs to be 3D printed has a size of c*d, c is the number of pixel points in the x direction, and d is the number of pixel points in the y direction, so there are c rows and d columns of pixel points; Step 2: A position and speed based 3D printing synchronous exposure system is built, wherein the light source comprises a rows of sub-light source groups, each group of sub-light source groups comprises b sub-light sources arranged side by side along the y-axis direction, and the light source movement system drives the a rows of sub-light source groups to pass above the image projection area; and a is less than c and b is less than d; For the image that needs to be 3D printed, the image is divided into a plurality of image projection sub-areas along the y direction, and the light source is controlled to perform 3D printing synchronous exposure on each image projection sub-area in turn; For any one image projection sub-area, the following method is used to control the light source to perform 3D printing synchronous exposure on the area: Step 2.1: Initially, the light source is at a position outside the image projection area, accelerates along the x direction, reaches a target speed before the position x=0 of the image projection sub-area, then moves at a constant speed using the target speed, and passes through the image projection area; First, the b sub-light sources of the first row of sub-light source groups pass through the position x=0 of the image projection sub-area, i.e., the first 1 sub-light source, the first 2 sub-light source, …, and the first b sub-light source reach the starting positions of the first row, the first column pixel point, the first row, the second column pixel point, …, and the first row, the b column pixel point of the image projection sub-area, respectively; Step 2.2: The light source movement system controls the light source to move at a constant speed along the x direction from the position x=0 above the image projection sub-area; From t=0, in the process of uniform motion of the light source, whenever the b sub-light sources of the arbitrary kth row sub-light source group move to the starting position of the ith row pixel point of the image projection sub-region, k=1, 2, …, a, i=1, 2, …, c, the b sub-light sources of the kth row sub-light source group are controlled to refresh the pixel point images of the corresponding pixel point positions at the same time, and the b sub-light sources of the kth row sub-light source group are turned on at the same time through the light source switch, so that the b sub-light sources of the kth row sub-light source group start exposure at the same time; Wherein, the b sub-light sources of the kth row sub-light source group are controlled to refresh the pixel point images of the corresponding pixel point positions, specifically: for the k-1th sub-light source, the k-2th sub-light source, …, the k-bth sub-light source, the pixel point images of the ith row, the first column pixel point, the ith row, the second column pixel point, …, the ith row, the bth column pixel point of the image projection sub-region are refreshed respectively; From the start of exposure of the b sub-light sources of the kth row sub-light source group, the light source exposure duration timer starts timing, when the continuous exposure time reaches the timing time length T, wherein the timing time length T is set, at this time the b sub-light sources of the kth row sub-light source group are still moving in the ith row pixel point, the b sub-light sources of the kth row sub-light source group are turned off at the same time through the light source switch, so that the b sub-light sources of the kth row sub-light source group end exposure at the same time; After the b sub-light sources of the kth row sub-light source group end exposure at the same time, when they move uniformly to the starting position of the next row of pixel points, the b sub-light sources of the kth row sub-light source group refresh the pixel point images at the same time again and start exposure; after the continuous exposure time, that is, the timing time length T, the b sub-light sources of the kth row sub-light source group are turned off at the same time, so that the b sub-light sources of the kth row sub-light source group end exposure at the same time; this cycle is repeated to realize the complete exposure of the image projection sub-region in pixel points during the process of uniform motion along the x direction; Step 2.2 is specifically: Step 2.2.1, assuming that the actual physical length of a single pixel point along the x direction is d microns; the coefficient of the x-axis direction displacement sensor is f, that is: the number of pulses generated by the displacement sensor per 1 micron of movement is 1 / f; the movement speed of the light source along the x direction is v pulses per millisecond; Step 2.2.2, in the process of uniform motion of the b sub-light sources of the kth row sub-light source group, the x-axis direction displacement sensor detects the displacement of the b sub-light sources of the kth row sub-light source group, and generates pulses at a certain frequency according to its coefficient f, and the generated pulses are sent to the first pulse receiving unit in real time; the first pulse receiving unit feeds back the received pulses to the image refresh controller; From t=0, the image refresh controller counts the number of pulses received from the first pulse receiving unit, and every time d / f pulses are received, b sub-sources of the kth row of sub-source groups move to the starting position of a column of pixel points, therefore, the image refresh controller controls the pulse sending unit to send a pulse to the second pulse receiving unit, and every time the second pulse receiving unit receives a pulse, it triggers the b sub-sources of the kth row of sub-source groups to perform pixel point image refresh and sub-source opening actions; Whenever the b sub-light sources of the kth row sub-light source group perform the action of pixel point image refreshing and sub-light source opening, the light source exposure duration timer is started simultaneously, and when the timing time length T is reached, the b sub-light sources of the kth row sub-light source group are closed simultaneously; the maximum value of the timing time length T is the maximum continuous exposure time t of the sub-light source max , satisfy the following inequality: t max <d / (v*f); Specifically, according to the on-off diagram of a single pixel point in the light source push-scan process, it can be seen that the exposure of a single pixel point is realized while the machine is moving. When a row of sub-light source groups moves to the starting position t0 of a row of pixel points, the sub-light sources of the row immediately expose. With the movement of the machine, the sub-light sources still in exposure will inevitably affect the projection of the next row of pixel points. It can be seen that the uniformity of the exposure effect of the light source at each position ultimately depends on whether the continuous exposure time of the light source after each image refresh is consistent. The continuous exposure time of the light source can be set according to the actual situation, that is, the value of the timing length T. The controllable range of the continuous exposure time of the light source is from the limit refresh interval of the light source itself to the time obtained by dividing the length of a single pixel point by the moving speed of the light source, that is, the maximum continuous exposure time t max of the light source. Based on the parameters of the image refresh signal, the moving speed of the light source is v pulses / millisecond. The time left for the light source to close the exposure. At this time, the maximum continuous exposure time t max of the light source should be less than d / (v*f). As can be seen from the continuous exposure time formula, d represents the actual physical length of a single pixel point in the x direction, and f represents the coefficient of the x-axis direction displacement sensor. Both are quantitative. Therefore, as long as the moving speed of the light source, that is, the speed of the machine in the push-scan direction, is unchanged, the continuous exposure time is unchanged. According to the relationship between speed and time, at this time, the moving position of the light source driven by the machine is also consistent, that is, from the beginning of exposure to the end of exposure, the position of the current pixel point entering the next row of pixel points is consistent. In this way, until the single image push-scan is completed, all pixel points are affected consistently, and finally the consistency of the exposure effect of each part of the projection area can be ensured.

2. The method of claim 1, wherein the method further comprises: The light source image refresh control system comprises an image refresh controller, an x-axis direction displacement sensor, a first pulse receiving unit, a pulse sending unit and a second pulse receiving unit. The x-axis direction displacement sensor is used to detect the displacement of the light source moving at a constant speed along the x-axis direction, and the output end of the x-axis direction displacement sensor is connected with the first pulse receiving unit; the output end of the first pulse receiving unit is connected with the image refresh controller; the output end of the image refresh controller is connected with the second pulse receiving unit; and the output end of the second pulse receiving unit is connected with the light source.

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