Single laser printing device and method capable of modulating line width

Abstract

The invention relates to a single laser printing device and method capable of modulating line width. The device comprises a focusing unit, a galvanometer unit, a light beam adjusting module and an angle adjusting module, wherein the light beam adjusting module and the angle adjusting module are sequentially arranged in front of laser light paths of the focusing unit and the galvanometer unit; the light beam adjusting module is used for modulating circular laser into long-strip-shaped laser and modulating the length of the long-strip-shaped laser according to the size of a pattern at a printing position when the same straight line is scanned; the long-strip-shaped light beams are always parallel to one another during galvanometer scanning, and laser energy in variable-width lines scanned by the galvanometer is evenly distributed. The angle adjusting module is used for adjusting the line width direction of the long-strip-shaped laser to be perpendicular to the scanning direction of the galvanometer unit. For different positions in each printing area, the laser is modulated into long-strip-shaped laser with the width consistent with the width of an image at the printing position through the light beam adjusting module, then the width direction of the long-strip-shaped laser is perpendicular to the scanning direction of the galvanometer through the angle adjusting module, and scanning of one printing area can be achieved only through one-time scanning of the galvanometer unit. And the printing precision is ensured while the printing efficiency is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing, and in particular relates to a single laser printing device and method with modulatable line width. Background Art

[0002] The function of an SLM metal 3D printer is to use metal powder to melt under the heat of a laser beam, cool, condense, and then stack layers to manufacture parts. SLM metal 3D printing has relatively high requirements for printing lasers. The laser beam needs to be pure single-mode output and the beam quality M2 is less than 1.1. Lasers with high beam quality usually have low laser power and cannot be used to further improve printing efficiency. In addition, the splashing of metal particles in metal 3D printing will seriously affect the printing quality. These are all common process problems in 3D printing.

[0003] Powder bed laser melting (PBL) focuses a high-energy fiber laser beam into a small spot with sufficient energy intensity to completely melt a thin layer of metal powder. A pair of scanning galvanometers moves the laser across the powder bed, where the metal powder melts and solidifies, connecting with the underlying layer and adjacent areas to form a molten pool. A protective airflow flows over the build plate, protecting the hot metal from oxidation and safely removing fumes. The molten pool is wider than the laser spot (approximately two to three times its diameter) because the heat generated by the laser conducts to the surrounding powder particles, melting them into the moving pool. Multiple melt tracks connect and overlap, forming a solid metal layer corresponding to the part's layering. The melt tracks must be deep enough to partially remelt the underlying metal layers, forming a fully dense, solid structure. Powder bed laser melting 3D printing machines build parts layer by layer in this manner.

[0004] According to the requirements of metal 3D printing process, it is usually necessary to meet the requirements of laser power P and scanning speed V to match each other appropriately, such as Figure 1 As shown, if the scanning speed is too fast and the laser power is too low, some areas of the part may not be completely melted, resulting in porosity due to "lack of melting". Conversely, if too much power is applied at the selected speed, the molten pool may overheat and the energy may penetrate too deeply, resulting in a "deep hole" effect. Between these two extremes is an "operating window" within which good part density can be obtained. Within this window, the laser energy is sufficient to completely melt the powder and the metal layer below it without penetrating too deeply. It can be seen that increasing the laser power and scanning speed simultaneously can improve processing efficiency, which is feasible to some extent. However, there is a limit to both power and speed. Once this limit is exceeded, the molten pool becomes unstable and a "spheroidization" effect occurs. As shown in Figure 2As shown in Figure 1, increasing laser power may also increase spatter, and when the scanning speed is too fast, the melt pool may become unstable. High surface tension gradients cause voids to form behind the laser beam, which expand as the laser moves, causing the melt pool to break up and eventually solidify into multiple disconnected spheres.

[0005] Therefore, in metal 3D printing, the above-mentioned process characteristics limit the ability to improve part printing efficiency by increasing the scanning speed. In order to improve printing efficiency, a larger spot and thicker scanning lines are usually used to print the filled part of the part, and a fine spot is used to print the stroke lines. Patent Nos. "CN8799127U" and "CN5867306U" respectively provide solutions for using thick lines and thin lines to scan the filled and stroked parts respectively through dual laser beams and optical zoom systems. In the above solutions, when printing any scan line, only one thickness can be selected. Since the pattern has a more complex structure, if the traditional fixed thickness scanning line is used for printing, the detailed structure of the pattern cannot be printed; in order to print the fine structure of the pattern, very fine laser beam lines are required to scan many times, which will greatly reduce the printing efficiency. Therefore, the traditional printing method cannot take into account both printing efficiency and printing accuracy at the same time. Summary of the Invention

[0006] The purpose of the present invention is to provide a single laser printing device and method with modulatable line width, so as to solve the problem that traditional 3D printing methods cannot take into account both printing efficiency and printing accuracy at the same time.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows: The present invention relates to a single laser printing device with modulatable line width, which comprises a focusing unit and a galvanometer unit arranged on a laser optical path, and further comprises a beam adjustment module and an angle adjustment module, wherein the beam adjustment module and the angle adjustment module are sequentially arranged in front of the focusing unit and the galvanometer unit in the laser optical path; The beam adjustment module is used to modulate a circular laser into a long strip of laser light, and when scanning the same straight line, modulate the length of the long strip of laser light at a time of microseconds according to the size of the pattern at the printing position; the long strips of light are always parallel to each other during the galvanometer scanning, so that the laser energy is evenly distributed within the variable width line scanned by the galvanometer.

[0008] The angle adjustment module is used to modulate the line width direction of the long strip laser to be perpendicular to the scanning direction of the galvanometer unit.

[0009] Preferably, the beam adjustment module adopts an acousto-optic modulator, which adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped, so that the laser spot in the round of modulation is adjusted at a speed of v 2 moves at a constant speed and forms a straight motion trajectory, and the speed at which the laser moves by the acousto-optic modulator is v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time points from the start of ultrasonic wave input to the AOM to the stop of ultrasonic wave input, so that the length and position of the motion trajectory are consistent with the image at the printing position.

[0010] Preferably, the beam adjustment module adopts a rotating mirror, which includes a plurality of reflective lenses, and the angles between adjacent reflective lenses are the same. By rotating the rotating mirror at a constant speed, the laser is reflected by the plurality of reflective lenses in sequence to form a plurality of motion tracks. The length of the motion track formed by each reflective lens is consistent with the width of the image at the printing position by coordinating with the laser switch; and the speed at which the laser moves is controlled by the rotating mirror. v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0011] Preferably, the angle adjustment module adopts a Dove prism, which includes two upper and lower reflecting surfaces and two left and right refractive surfaces. The long strip laser enters the Dove prism through one of the refractive surfaces, and is reflected by the two reflecting surfaces in the Dove prism and then emitted from the other refractive surface. The length direction of the long strip laser after emitting the Dove prism is adjusted by rotating the Dove prism so that it is perpendicular to the scanning direction of the galvanometer unit.

[0012] Preferably, the angle of the angle adjustment module when the length direction of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit is taken as its initial angle, and the rotation angle of the angle adjustment module is calculated according to the vector of the image at the printing position. The calculation formula is: , in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module.

[0013] The present invention also relates to a single laser printing method with modulated line width, which comprises the following steps: S0 according to the maximum width of the long laser beam adjustment module modulation print work area is divided into several printing units, for each printing unit, respectively, in accordance with the order of S1-S3 printing; S1. A beam adjustment module is used to modulate a circular laser into a long laser strip. When scanning the same straight line, the length of the long laser strip is modulated in microseconds according to the size of the pattern at the printing position. S2. The line width direction of the long laser is modulated to be perpendicular to the scanning direction of the galvanometer unit through the angle adjustment module; S3. The long laser strip is focused by the focusing unit and reflected onto the printing surface by the galvanometer unit, completing printing at that location. The galvanometer unit is then rotated to move the long laser strip to the next printing location and return to S1 until printing is complete at all locations.

[0014] Preferably, the beam adjustment module in S1 adopts an acousto-optic modulator, which adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped, so that the laser spot in the round of modulation is adjusted at a speed of v 2 moves at a constant speed and forms a straight motion trajectory, and the speed at which the laser moves by the acousto-optic modulator is v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time points from the start of ultrasonic wave input to the AOM to the stop of ultrasonic wave input, so that the length and position of the motion trajectory are consistent with the image at the printing position.

[0015] Preferably, the beam adjustment module in S1 adopts a rotating mirror, which includes multiple reflective lenses. The angles between adjacent reflective lenses are the same. By rotating the rotating mirror at a constant speed, the laser is reflected by multiple reflective lenses in sequence to form multiple motion tracks. The length of the motion track formed by each reflective lens is consistent with the image width at the printing position by coordinating with the laser switch; and the speed at which the laser moves is v 2 Satisfaction v 2 / v1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0016] Preferably, the angle adjustment module in S2 adopts a Dove prism, which includes two upper and lower reflecting surfaces and two left and right refractive surfaces. The long strip laser enters the Dove prism through one of the refractive surfaces, and is reflected by the two reflecting surfaces in the Dove prism and then emitted from the other refractive surface. The length direction of the long strip laser after emitting the Dove prism is adjusted by rotating the Dove prism so that it is perpendicular to the scanning direction of the galvanometer unit.

[0017] Preferably, in S2, the angle of the angle adjustment module when the length direction of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit is its initial angle, and the rotation angle of the angle adjustment module is calculated according to the vector of the image at the printing position, and the calculation formula is: , in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module.

[0018] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention relates to a single-laser printing device with modulatable line width, comprising a beam adjustment module and an angle adjustment module. The beam adjustment module is used to modulate a circular laser beam into a long laser strip with a line width consistent with the image width at the printing location. The angle adjustment module is used to modulate the line width of the long laser strip to be perpendicular to the scanning direction of the galvanometer unit. Beam modulation increases the beam width, allowing the galvanometer unit to scan each printing area only once. The laser can also be turned on and off to scan patterns with finer lines. The pattern printing accuracy remains unchanged compared to single-beam laser scanning printing, significantly improving printing efficiency while maintaining printing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the relationship between laser power and scanning speed during SLM metal 3D printing; Figure 2 Schematic diagram of the phenomenon of unstable molten pool caused by excessive scanning speed; Figure 3 This is a schematic structural diagram of a front-focused single laser printing device with modulated line width according to the present invention; Figure 4 This is a schematic structural diagram of a post-focusing single laser printing device with modulated line width according to the present invention; Figure 5 This is a schematic diagram of the long strip laser modulation principle using an acousto-optic modulator as a beam adjustment module in Example 1; Figure 6 A Dove prism with 1 reflection; Figure 7 Dove prism to increase the length of the reflecting surface; Figure 8 Dove prism to change the shape of the reflecting surface; Figure 9 This is a diagram showing the process of adjusting long laser strips of different widths by using an acousto-optic modulator in Example 1; Figure 10 This is a schematic structural diagram of the rotating mirror in Example 2; Figure 11 This is a schematic diagram of the long strip laser modulation principle using a rotating mirror as a beam adjustment module in Example 2; Figure 12 This is a diagram showing the process of adjusting the long laser strips of different widths by rotating the mirror in Example 2; Among them, 1-beam adjustment module, 2-angle adjustment module, 3-focusing unit, 4-galvanometer unit, 5-printing work surface. DETAILED DESCRIPTION

[0020] In order to further understand the content of the present invention, the present invention is described in detail with reference to the examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0021] Example 1: The present invention relates to a single laser printing device with adjustable line width, which comprises a focusing unit 3, a galvanometer unit 4, a beam adjustment module 1 and an angle adjustment module 2 arranged on the laser light path. Figure 3 The front focusing lens group shown in the figure is an imaging lens group composed of several convex lenses and concave lenses; the focusing unit 3 can also adopt Figure 4 In the rear focusing mode shown, the focusing unit 3 uses an FTheta field mirror. The galvanometer unit 4 includes an X-axis galvanometer and a Y-axis galvanometer. The beam adjustment module 1 and the angle adjustment module 2 are sequentially arranged in front of the focusing unit 3 and the galvanometer unit 4.

[0022] The beam adjustment module 1 is used to modulate the circular laser into a long strip laser, and when scanning the same straight line, the length of the long strip laser is modulated at a time of microseconds according to the size of the pattern at the printing position; in this embodiment, the beam adjustment module 1 adopts an acousto-optic modulator, and the principle of the acousto-optic modulator modulating the circular laser into a long strip laser is as follows: Acousto-optic modulation is to modulate the signal in the acousto-optic crystal, act on the ultrasonic transducer in the form of an electrical signal, and then convert it into a mechanical ultrasonic field that changes in the form of an electrical signal. When the light wave passes through the medium, the direction of the light beam is deflected due to the grating diffraction effect, where the light beam deflection angle is related to the ultrasonic frequency input to the acousto-optic modulator. This is the basic knowledge of the acousto-optic modulator and will not be repeated here. Therefore, this embodiment adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. During each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped, so that the laser spot in this round of modulation is tangent or partially overlapped at a speed. v 2 moves at a constant speed and forms a straight motion trajectory, and the speed at which the laser moves by the acousto-optic modulator is v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. In this way, the speed at which the acousto-optic modulator moves the laser is v 2Much greater than the scanning speed of the galvanometer unit v 1. As Figure 5 As shown, the acousto-optic modulator first deflects the first-order light diffraction angle to θ 1. The beam spot at this angle hits θ 1 position, and then the acousto-optic modulator changes the ultrasonic frequency to deflect the first-order light diffraction angle to θ 2. The beam spot at this angle hits the θ 2 position, θ 2 and θ 1 adjacent, of course, can also be partially overlapped, this embodiment is only adjacent as an example; repeat the above operation, so that the spot is hit on θ 3~ θ 6 positions, the switching time between each spot is 0.2us, the diameter D of each spot is 100um, and the scanning speed of the galvanometer is v 1=2000mm / s, that is, when the AOM is fed θ 1~ θ 6 corresponding to the ultrasonic wave, the circular spot forms a motion trajectory of the ratio, and the speed of the laser movement caused by the acousto-optic modulator is v 2Much greater than the scanning speed of the galvanometer unit v1. The motion trajectory can be regarded as a long strip of laser beam relative to the scanning direction of the galvanometer. Theoretically, since the length direction of the long strip of laser beam needs to be modulated to be perpendicular to the scanning direction of the galvanometer in the subsequent scanning process, there is an angle between the angle increase of the acousto-optic modulator and the scanning direction of the galvanometer. α , similarly, the speed at which the laser moves due to the AOM v 2Much greater than the scanning speed of the galvanometer unit v 1, α ≈90°, and when θ 1~ θ When the corresponding ultrasonic signal is input at each position 6, the width H of the long laser strip can be equal to 6 times the diameter of the original circular laser. The width H of the long laser strip is the maximum printing width of the single scan of the printing device.

[0023] The angle adjustment module 2 is used to modulate the line width direction of the long laser strip to be perpendicular to the scanning direction of the galvanometer unit. The angle adjustment module 2 adopts a Dove prism, which includes two upper and lower reflective surfaces and two left and right refractive surfaces. The long laser strip enters the Dove prism through one of the refractive surfaces, and is reflected by the two reflective surfaces in the Dove prism before being emitted from the other refractive surface. The length direction of the long laser strip after being emitted from the Dove prism is adjusted by rotating the Dove prism so that it is perpendicular to the scanning direction of the galvanometer unit. The number of reflections of the Dove prism is at least 1, such as Figure 6 As shown, it is also possible to increase the length of the reflecting surface (such as Figure 7 ) or changing the shape of one of the reflecting surfaces into an isosceles triangle reflecting surface (as Figure 8 The number of reflections is increased by the method shown in FIG. 1 ) to improve the sensitivity of linewidth modulation.

[0024] Based on the above-mentioned single laser printing device with modulated line width, the single laser printing method with modulated line width of this embodiment includes the following steps: S0. According to the beam adjustment module, the maximum width H of the long laser strip is modulated to divide the printing work surface into several printing units, that is, the width of each printing unit is not greater than the maximum width H of the long laser strip, preferably equal to the maximum width H. For each printing unit, printing is performed in the order of S1-S3; S1. The beam adjustment module is used to modulate the circular laser into a long strip laser. When scanning the same straight line, the length of the long strip laser is modulated in microseconds according to the size of the pattern at the printing position. The acousto-optic modulator adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. During each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped. The specific modulation method is: the length and starting position of the motion trajectory are controlled by the time point from the start of ultrasonic input to the acousto-optic modulator to the stop of ultrasonic input, so that the length and position of the motion trajectory are consistent with the image at the printing position, such as Figure 9 As shown, when printing the first printing position from left to right, the AOM cyclically inputs an ultrasonic signal of the response frequency at 6 time points. When printing the second printing position from left to right, the AOM does not input an ultrasonic signal at the first time point, and cyclically inputs an ultrasonic signal of the response frequency at the 2nd to 6th time points, and so on. S2. Use the angle adjustment module to modulate the line width of the long laser strip to be perpendicular to the scanning direction of the galvanometer unit. The initial angle of the angle adjustment module is when the length of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit. Calculate the rotation angle of the angle adjustment module based on the vector of the image at the printing position. The calculation formula is: , in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module; S3. Focus the long laser strip through the focusing unit 3, and reflect the long laser strip onto the printing work surface 5 through the galvanometer unit 4 to complete the printing at that position. Then, the long laser strip is moved to the next printing position by rotating the galvanometer unit 4, and returns to S1 until the printing of all positions is completed.

[0025] Example 2 Compared with Example 1, this embodiment adopts a rotating mirror instead of the acousto-optic modulator in the embodiment as the beam adjustment module 1. The specific structure of the rotating mirror is as follows: Figure 10 As shown, it includes multiple reflective lenses, and the angles between adjacent reflective lenses are the same. By rotating the mirror at a constant speed, the laser is reflected by multiple reflective lenses in sequence to form multiple motion tracks. With the laser switch, the length of the motion track formed by each reflective lens is consistent with the image width at the printing position; and the speed at which the laser moves is v2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

[0026] The principle of the rotating mirror modulating the circular laser into a long strip laser is as follows: the scanning and printing speed of the galvanometer unit 4 is usually very slow. Taking the commonly used scanning speed of metal 3D printing as an example, the scanning speed at the printing working surface is usually 1000~2000mm / s, and the working distance of the galvanometer unit 4 is 400~800mm. Calculated at a scanning speed of 2000mm / s and a working distance of 500mm, the scanning angular velocity of the laser beam is 4rad / s, and the rotation angular velocity of the unit 4 is 2rad / s, that is, 19.1 revolutions per minute. Usually, the rotation speed of the rotating mirror can exceed 60,000 revolutions per minute, so the angular velocity of the rotating mirror exceeds 3000 times the working angular velocity of the galvanometer. Figure 11 As shown in the figure, when the circular laser hits the edge of a certain reflective lens of the rotating mirror, the rotating mirror rotates at a uniform speed, and the circular light spot forms a motion trajectory of a ratio. Since the rotation speed of the rotating mirror is much greater than the rotation speed of the galvanometer unit, the motion trajectory can be regarded as a long strip of laser beam relative to the scanning direction of the galvanometer. The scanning distance of the single-sided reflective lens is the length H of the motion trajectory. From a theoretical analysis, since the length direction of the long strip of laser beam needs to be modulated to be perpendicular to the scanning direction of the galvanometer in the subsequent scanning process, there is an angle between the scanning direction of the rotating mirror and the scanning direction of the galvanometer. α ,Similarly, since the rotation speed of the rotating mirror is much greater than the rotation speed of the galvanometer unit, α ≈90°. The width H of this long laser strip is the maximum print width of a single scan of the printing device. Assuming the reflective element of the rotating mirror is equilateral and N-sided, the equivalent scanning distance of the rotating mirror is L. As the rotating mirror rotates, the angle that the laser can scan through each edge is 4π / N. For more flexible scanning patterns, a polygonal rotating mirror with a large N is usually selected. When N is relatively large, the scanning length H of the laser beam on the printing surface after passing through the rotating mirror can be approximately expressed as: H = 4πL / N.

[0027] Based on the above-mentioned single laser printing device with modulated line width, the single laser printing method with modulated line width of this embodiment includes the following steps: S0. According to the beam adjustment module, the maximum width H of the long laser strip is modulated to divide the printing work surface into several printing units, that is, the width of each printing unit is not greater than the maximum width H of the long laser strip, preferably equal to the maximum width H. For each printing unit, printing is performed in the order of S1-S3; S1. The beam adjustment module is used to modulate the circular laser into a long strip laser. When scanning the same straight line, the length of the long strip laser is modulated in microseconds according to the size of the pattern at the printing position. The laser is reflected by multiple reflective lenses in sequence by rotating the mirror at a uniform speed to form multiple motion tracks. The length of the motion track formed by each reflective lens is consistent with the image width at the printing position by coordinating the laser switch. The specific modulation method is: the length of the motion track formed by each reflective lens is consistent with the image width at the printing position by coordinating the laser switch, such as Figure 12 As shown, when the rotating mirror scans to the dotted line position, the laser is turned off, and when the rotating mirror scans to the solid line position, the laser is turned on to adapt to the image width at different positions; S2. Use the angle adjustment module to modulate the line width of the long laser strip to be perpendicular to the scanning direction of the galvanometer unit. The initial angle of the angle adjustment module is when the length of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit. Calculate the rotation angle of the angle adjustment module based on the vector of the image at the printing position. The calculation formula is: , in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module; S3. Focus the long laser strip through the focusing unit 3, and reflect the long laser strip onto the printing work surface 5 through the galvanometer unit 4 to complete the printing at that position. Then, the long laser strip is moved to the next printing position by rotating the galvanometer unit 4, and returns to S1 until the printing of all positions is completed.

[0028] The present invention has been described in detail above with reference to the embodiments. However, the contents described are only preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A single laser printing device with adjustable line width, comprising a focusing unit and a galvanometer unit arranged on the laser light path, characterized in that: It also includes a beam adjustment module and an angle adjustment module, which are sequentially arranged in front of the laser light path of the focusing unit and the galvanometer unit; The beam adjustment module is used to modulate the circular laser into a long laser strip. When scanning the same straight line, the length of the long laser strip is modulated in microseconds according to the size of the pattern at the printing position. The long laser strips are always parallel to each other during the galvanometer scanning, so that the laser energy is evenly distributed within the variable width line scanned by the galvanometer. The angle adjustment module is used to modulate the line width direction of the long strip laser to be perpendicular to the scanning direction of the galvanometer unit.

2. The single laser printing device with adjustable line width according to claim 1, characterized in that: The beam adjustment module adopts an acousto-optic modulator, which adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped, so that the laser spot in the round of modulation is adjusted at a speed of v 2 moves at a constant speed and forms a straight motion trajectory, and the speed at which the laser moves by the acousto-optic modulator is v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time points from the start of ultrasonic wave input to the AOM to the stop of ultrasonic wave input, so that the length and position of the motion trajectory are consistent with the image at the printing position.

3. The single laser printing device with adjustable line width according to claim 1, characterized in that: The beam adjustment module adopts a rotating mirror, which includes multiple reflective lenses. The angles between adjacent reflective lenses are the same. By rotating the rotating mirror at a constant speed, the laser is reflected by multiple reflective lenses in turn to form multiple motion tracks. The length of the motion track formed by each reflective lens is consistent with the image width at the printing position by coordinating with the laser switch. The rotating mirror makes the laser move at a speed of v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

4. The single laser printing device with adjustable line width according to claim 1, characterized in that: The angle adjustment module adopts a Dove prism, which includes two upper and lower reflecting surfaces and two left and right refractive surfaces. The long strip laser enters the Dove prism through one of the refractive surfaces, is reflected by the two reflecting surfaces in the Dove prism, and then is emitted from the other refractive surface. The length direction of the long strip laser after emitting the Dove prism is adjusted by rotating the Dove prism so that it is perpendicular to the scanning direction of the galvanometer unit.

5. The single laser printing device with adjustable line width according to claim 4, characterized in that: The initial angle of the angle adjustment module is when the length direction of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated based on the vector of the image at the printing position. The calculation formula is: ， in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module.

6. A single laser printing method with adjustable line width, characterized in that: It includes the following steps: S0 according to the maximum width of the long laser beam adjustment module modulation print work area is divided into several printing units, for each printing unit, respectively, in accordance with the order of S1-S3 printing; S1. A beam adjustment module is used to modulate a circular laser into a long laser strip. When scanning the same straight line, the length of the long laser strip is modulated in microseconds according to the size of the pattern at the printing position. S2. The line width direction of the long laser is modulated to be perpendicular to the scanning direction of the galvanometer unit through the angle adjustment module; S3. Focus the long laser strip through the focusing unit, and reflect the long laser strip onto the printing work surface through the galvanometer unit to complete printing at that position. Then, move the long laser strip to the next printing position by rotating the galvanometer unit and return to S1 until printing is completed at all positions.

7. The single laser printing method with adjustable line width according to claim 6, characterized in that: The beam adjustment module in S1 adopts an acousto-optic modulator, which adjusts the diffraction angle of the laser by continuously modulating the ultrasonic frequency. In each round of modulation, the interval period of each modulation of the ultrasonic frequency is the same, and the laser spot before and after each modulation is tangent or partially overlapped, so that the laser spot in the round of modulation is adjusted at a speed of v 2 moves at a constant speed and forms a straight motion trajectory, and the speed at which the laser moves by the acousto-optic modulator is v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position. The length and starting position of the motion trajectory are controlled by the time points from the start of ultrasonic wave input to the AOM to the stop of ultrasonic wave input, so that the length and position of the motion trajectory are consistent with the image at the printing position.

8. The single laser printing device with adjustable line width according to claim 6, characterized in that: The beam adjustment module in S1 adopts a rotating mirror, which includes multiple reflective lenses. The angles between adjacent reflective lenses are the same. By rotating the rotating mirror at a constant speed, the laser is reflected by multiple reflective lenses in turn to form multiple motion tracks. The length of the motion track formed by each reflective lens is consistent with the image width at the printing position by coordinating with the laser switch. The rotating mirror makes the laser move at a speed of v 2 Satisfaction v 2 / v 1≥H / D, where v 1 represents the scanning speed of the galvanometer unit, D is the spot diameter, and H is the width of the image at the scanning position.

9. The single laser printing device with adjustable line width according to claim 6, characterized in that: The angle adjustment module in S2 adopts a Dove prism, which includes two upper and lower reflecting surfaces and two left and right refractive surfaces. The long strip laser enters the Dove prism through one of the refractive surfaces, and is reflected by the two reflecting surfaces in the Dove prism and then emitted from the other refractive surface. The length direction of the long strip laser after emitting the Dove prism is adjusted by rotating the Dove prism so that it is perpendicular to the scanning direction of the galvanometer unit.

10. The single laser printing device with adjustable line width according to claim 9, characterized in that: In S2, the angle of the angle adjustment module is taken as its initial angle when the length direction of the long laser strip is parallel to the Y-axis scanning direction of the galvanometer unit. The rotation angle of the angle adjustment module is calculated according to the vector of the image at the printing position. The calculation formula is: ， in, β is the rotation angle of the angle adjustment module, ( a 1, b 1) and ( a 2, b 2) are the starting and ending coordinates of the vector of the image at the printing position, k is the number of reflections of the long laser strip in the angle adjustment module.

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