Laser marking equipment and laser marking method

Abstract

The present invention discloses a laser marking device and a laser marking method. The laser marking device includes a femtosecond laser, a beam expander, an acousto-optic deflector, a reflector module, a galvanometer module and a coaxial positioning camera. The femtosecond laser is used to output a femtosecond laser beam. The beam expander is arranged at the laser output end of the femtosecond laser. The acousto-optic deflector is arranged at the laser output end of the beam expander. The reflector module is arranged at the laser output end of the acousto-optic deflector. The galvanometer module is arranged at the first side of the reflector module and is located on the reflected light path. The laser output end of the galvanometer module is provided with a lens. The coaxial positioning camera and the galvanometer module are distributed on opposite sides of the reflector module. The acousto-optic deflector is used to deflect the femtosecond laser beam at a random angle to generate a light spot with a random position in the scanning area of ​​the galvanometer module. The present invention can be used for marking transparent films.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and in particular to a laser marking device and a laser marking method. Background Art

[0002] With the continuous development of the petrochemical industry, the variety of plastic films continues to increase. These films have the advantages of being waterproof, dustproof, anti-oxidant, heat-resistant, and transparent, and are widely used in industries such as food, medical, cosmetics, electronics, and various product protective films. With the large-scale application of various plastic films, whether it is quality control in the production process or information identification on the final product, it is necessary to mark text or barcodes on the film. However, transparent films have a high transmittance to conventional nanosecond lasers, making it difficult to form effective markings on transparent films. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a laser marking device and a laser marking method, which can be used for marking a transparent film.

[0004] On the one hand, an embodiment of the present invention provides a laser marking device, which is suitable for marking transparent films, and includes a femtosecond laser, a beam expander, an acousto-optic deflector, a reflector module, a galvanometer module and a coaxial positioning camera, wherein the femtosecond laser is used to output a femtosecond laser beam, the beam expander is arranged at the laser output end of the femtosecond laser, the acousto-optic deflector is arranged at the laser output end of the beam expander, the reflector module is arranged at the laser output end of the acousto-optic deflector, the galvanometer module is arranged on a first side of the reflector module and is located on a reflected light path, a lens is arranged at the laser output end of the galvanometer module, and the coaxial positioning camera and the galvanometer module are distributed on opposite sides of the reflector module; wherein the acousto-optic deflector is used to deflect the femtosecond laser beam at a random angle to generate light spot landing points with random positions within the scanning area of ​​the galvanometer module.

[0005] According to some embodiments of the present invention, the femtosecond laser is an infrared femtosecond laser, an ultraviolet femtosecond laser, or a green femtosecond laser.

[0006] According to some embodiments of the present invention, the laser wavelength of the femtosecond laser is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

[0007] According to some embodiments of the present invention, the beam expander is an adjustable zoom beam expander.

[0008] On the other hand, an embodiment of the present invention further provides a laser marking method suitable for marking of a transparent film, comprising:

[0009] Placing the transparent film in a laser marking area, wherein a galvanometer module is arranged in the laser marking area;

[0010] Outputting a femtosecond laser beam through a femtosecond laser, and performing beam expansion processing on the femtosecond laser beam through a beam expander;

[0011] Deflecting the femtosecond laser beam after beam expansion at random angles through an acousto-optic deflector, and outputting the femtosecond laser beam to the galvanometer module through a reflector module;

[0012] Based on a random position scanning method, the transparent film is laser marked within the scanning area of ​​the galvanometer module.

[0013] According to some embodiments of the present invention, the femtosecond laser is an infrared femtosecond laser, an ultraviolet femtosecond laser, or a green femtosecond laser, and the output of the femtosecond laser beam by the femtosecond laser includes one of the following:

[0014] Outputting an infrared femtosecond laser beam through an infrared femtosecond laser;

[0015] Alternatively, an ultraviolet femtosecond laser beam is outputted by an ultraviolet femtosecond laser;

[0016] Alternatively, a green femtosecond laser beam is outputted by a green femtosecond laser.

[0017] According to some embodiments of the present invention, the laser wavelength of the femtosecond laser is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

[0018] According to some embodiments of the present invention, the scanning area of ​​the galvanometer module covers the target mark of the transparent film, and the method based on random position scanning, laser marking the transparent film in the scanning area of ​​the galvanometer module, includes:

[0019] Based on the random position scanning method, the transparent film is laser marked in the scanning area of ​​the galvanometer module to complete the entire marking of the target logo.

[0020] According to some embodiments of the present invention, the scanning area of ​​the galvanometer module covers a part of the target mark of the transparent film, and the method based on random position scanning, laser marking the transparent film in the scanning area of ​​the galvanometer module, includes:

[0021] Based on the random position scanning method, the transparent film is laser marked in the scanning area of ​​the galvanometer module to complete the local marking of the target mark;

[0022] The galvanometer module is moved to the next marking position, and based on a random position scanning method, the transparent film is laser marked in the scanning area of ​​the galvanometer module until the marking of the target mark is completed.

[0023] According to some embodiments of the present invention, placing the transparent film in the laser marking area further comprises:

[0024] The galvanometer module is controlled to move to a marking processing position of the transparent film.

[0025] The embodiments of the present invention have at least the following beneficial effects:

[0026] Femtosecond lasers can generate extremely high power density in an instant, which can induce nonlinear absorption in transparent film materials and form laser marks on transparent films. The acousto-optic deflector is used to deflect the femtosecond laser beam at random angles to generate light spots with random positions within the scanning area of ​​the galvanometer module, thus avoiding deformation of the transparent film due to heat accumulation during the laser marking process.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 A schematic diagram of the laminated structure of a PDLC dimming film of the related art;

[0030] Figure 2 A schematic diagram of the principle of a laser marking device according to an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of a laser scanning path of a laser marking device according to an embodiment of the present invention;

[0032] Figure 4 A schematic diagram of a laser scanning path in the related art;

[0033] Figure 5 The figure is a flowchart of the steps of the laser marking method according to an embodiment of the present invention.

[0034] Reference numerals:

[0035] PDLC layer 10 , ITO conductive layer 11 , PET layer 12 , PET protective film 13 , femtosecond laser 100 , beam expander 200 , acousto-optic deflector 300 , reflector module 400 , galvanometer module 500 , coaxial positioning camera 600 , and lens 700 . DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0037] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, "several" means one or more, "multiple" means more than two, greater than, less than, and exceeding are understood as not including the number itself, and "above", "below", and "within" are understood as including the number itself. If there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0039] In the description of the present invention, unless otherwise clearly defined, words such as “setting”, “installation” and “connection” should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0040] With the extensive application of various plastic films, whether it is quality control in the production process or information identification on the final product, it is necessary to mark text or barcodes on the film. The related technology usually adopts the method of inkjet or label paper pasting, but the cost of inkjet printing consumables is high, and the content of the coding may be wiped off by solvents such as alcohol. The method of pasting label paper will increase the process, and the label paper is easy to wear, which may cause information loss. Whether inkjet printing or label paper pasting, because it can be erased and re-pasted, there is a problem of re-marking or pasting of inventory products, and there are risks in product quality, especially in the field of food packaging. Inkjet printing and label paper pasting methods both require the use of ink, which will inevitably cause certain pollution to the environment. For some colored plastic film surfaces, lasers are also used to mark information. However, for transparent film materials, since transparent materials have a high transmittance to lasers, conventional laser systems and processes cannot effectively mark transparent films.

[0041] For example, please refer to Figure 1 , taking PDLC (polymer dispersed liquid crystal) dimming film as an example, the common PDLC conductive film structure includes PDLC layer 10, ITO (indium tin oxide) conductive layer 11, PET (polyethylene terephthalate) layer 12 and PET protective film 13. During the production process, it is necessary to mark the PET protective film 13 with text and QR code to ensure the traceability of materials during the production process and the control of product quality. The usual operation is to use label paper for pasting, but during the production process, some processes will use solvents such as alcohol to clean the surface of the product and other locations. If the operator is not careful, the label paper will be corroded by the solvent, causing damage to the label paper information, posing risks to product traceability and quality control.

[0042] As for the laser marking method, commonly used laser marking uses infrared, ultraviolet or CO2 lasers, and the pulse width is mainly nanoseconds. Since the wavelength of CO2 laser is relatively large, which is 10.6μm, the thermal effect is large, and a small spot cannot be obtained, and precise marking cannot be achieved. The transparent film material has a large transmittance to infrared and ultraviolet nanosecond lasers, and it is impossible to focus and mark on the film layer. Most of the laser passes through the film material, causing damage to the ITO conductive layer 11 and PDLC layer 10 under the film, and it is also impossible to achieve a marking effect that meets the requirements. For this reason, this embodiment discloses a laser marking device and a laser marking method, which can be used to mark transparent films.

[0043] Please refer to Figure 2 The present embodiment discloses a laser marking device, which is suitable for marking transparent thin films, and includes a femtosecond laser 100, a beam expander 200, an acousto-optic deflector 300, a reflector module 400, a galvanometer module 500 and a coaxial positioning camera 600. The femtosecond laser 100 is used to output a femtosecond laser beam, the beam expander 200 is arranged at the laser output end of the femtosecond laser 100, the acousto-optic deflector 300 is arranged at the laser output end of the beam expander 200, and the reflector module 400 is arranged The laser output end of the acousto-optic deflector 300 is arranged, the galvanometer module 500 is arranged on the first side of the reflector module 400 and is located on the reflected light path, the laser output end of the galvanometer module 500 is provided with a lens 700, and the coaxial positioning camera 600 and the galvanometer module 500 are distributed on opposite sides of the reflector module 400; wherein the acousto-optic deflector 300 is used to deflect the femtosecond laser beam at a random angle to generate a light spot with a random position in the scanning area of ​​the galvanometer module 500. Among them, the beam expander 200 is an adjustable variable beam expander, which can eliminate the influence of the divergence angle within a certain range, thereby obtaining a laser beam with good collimation, and then obtaining a small high-power density light spot.

[0044] Femtosecond laser is a kind of laser that operates in the form of pulses. Its duration is very short, only a few femtoseconds. One femtosecond is 10 -15 Seconds. Since the extremely short pulse width of the femtosecond laser can generate extremely high power density in an instant, it can induce nonlinear absorption in the material. The laser energy will be absorbed on the surface of the transparent film and will not penetrate the film to cause damage to the structure below the film, thus achieving laser marking on the film surface.

[0045] In addition, since the thickness of transparent film materials is very small, taking the PDLC dimming film as an example, the thickness of the PET protective film 13 is only 50μm. Although the pulse width of the femtosecond laser is extremely short and basically has no thermal effect, under short-term high-frequency application, the film will still be deformed due to the accumulation of heat, especially when marking a two-dimensional code. The generation of the two-dimensional code needs to be obtained by filling countless laser pulses, which is more prone to deformation. In view of this situation, this embodiment sets an acousto-optic deflector 300 (AODF) on the transmission optical path of the laser. The acousto-optic deflector 300 can perform precise spatial control of the light beam to achieve scanning at random positions (such as Figure 3 As shown in the figure), changing the sequential filling processing path of the conventional galvanometer scanning system (as shown in the figure) Figure 4 ), where Figure 3 and Figure 4 The mark a in the middle indicates the spot where the light spot falls.

[0046] Among them, the acousto-optic deflector 300 can be understood as consisting of a transparent crystal with a piezoelectric transducer bonded to its side. When driven by radio frequency, the piezoelectric transducer generates sound waves (pressure / density) in the crystal. This causes the refractive index of the crystal to produce variable and periodic spatial changes, which is similar to the effect of a Bragg diffraction grating. This grating deflects the input laser beam, and the degree of deflection depends on its period. Therefore, changing the frequency of the radio frequency input signal can change the deflection angle of the laser beam. Since the acousto-optic deflector 300 does not have any moving mechanical parts, that is, there is no movement inertia of mechanical parts, the acousto-optic deflector 300 can achieve a much higher scanning speed than other technologies, which can reach the megahertz (MHz) level, and can achieve random scanning angle changes, that is, quickly jump from one point in the scanning field to another. Since the acousto-optic deflector 300 adopts a random scanning method, the landing position of each laser pulse is random, which greatly avoids the heat accumulation caused by high-frequency pulses, thereby avoiding thermal deformation of the film.

[0047] Therefore, the femtosecond laser can generate extremely high power density in an instant, can induce nonlinear absorption in transparent film materials, and can form laser marks on transparent films. The acousto-optic deflector 300 is used to deflect the femtosecond laser beam at random angles to generate light spots with random positions within the scanning area of ​​the galvanometer module 500, thereby avoiding deformation of the transparent film due to heat accumulation during the laser marking process, thereby enabling laser marking on the transparent film.

[0048] The femtosecond laser 100 is an infrared femtosecond laser, an ultraviolet femtosecond laser or a green femtosecond laser. For example, the laser wavelength of the femtosecond laser 100 is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

[0049] Please refer to Figure 2 and Figure 5 This embodiment also provides a laser marking method suitable for marking transparent films, including steps S100 to S400. It should be noted that the steps in this embodiment are numbered only for the convenience of review and understanding, rather than limiting the execution order of the steps. The contents of each step are described in detail below:

[0050] S100, placing a transparent film in a laser marking area, wherein a galvanometer module 500 is arranged in the laser marking area;

[0051] S200, outputting a femtosecond laser beam through the femtosecond laser 100, and performing beam expansion processing on the femtosecond laser beam through the beam expander 200;

[0052] S300, the femtosecond laser beam that has undergone beam expansion is randomly deflected by the acousto-optic deflector 300, and the femtosecond laser beam is output to the galvanometer module 500 by the reflector module 400;

[0053] S400 , based on a random position scanning method, laser marking is performed on the transparent film within the scanning area of ​​the galvanometer module 500 .

[0054] Exemplarily, the galvanometer module 500 is located above the laser marking area. The structure and working principle of the laser marking device corresponding to the galvanometer module 500 can be referred to above and will not be described in detail here. It should be noted that during the scanning process, the landing position of the laser beam is controlled by the acousto-optic deflector 300, and the galvanometer module 500 does not need to perform position scanning.

[0055] Femtosecond lasers can generate extremely high power density in an instant, which can induce nonlinear absorption in transparent film materials and form laser marks on transparent films. The acousto-optic deflector 300 is used to deflect the femtosecond laser beam at random angles to generate light spots with random positions within the scanning area of ​​the galvanometer module 500, thereby preventing deformation of the transparent film due to heat accumulation during the laser marking process, thereby enabling laser marking on the transparent film.

[0056] The femtosecond laser 100 is an infrared femtosecond laser, an ultraviolet femtosecond laser or a green femtosecond laser. Step S200, outputting a femtosecond laser beam through the femtosecond laser 100, includes one of the following:

[0057] S210, outputting an infrared femtosecond laser beam through the infrared femtosecond laser 100;

[0058] Alternatively, S220, outputting an ultraviolet femtosecond laser beam through the ultraviolet femtosecond laser 100;

[0059] Alternatively, S230 , output a green femtosecond laser beam through the green femtosecond laser 100 .

[0060] Transparent films can be laser-marked by lasers of different wavelengths, and in industrial applications, the infrared femtosecond laser 100 has a higher cost-performance ratio. For example, the laser wavelength of the femtosecond laser 100 is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

[0061] In some application examples, the scanning area of ​​the galvanometer module 500 covers the target mark on the transparent film, and step S400, based on the random position scanning method, laser marking the transparent film in the scanning area of ​​the galvanometer module 500 includes:

[0062] S410 , based on a random position scanning method, laser marking is performed on the transparent film within the scanning area of ​​the galvanometer module 500 to complete the marking of the target logo.

[0063] Exemplarily, the galvanometer module 500 is internally provided with a first reflector for scanning in the X direction and a second reflector for scanning in the Y direction, and the first reflector and the second reflector are both driven by a galvanometer motor, thereby forming a rectangular scanning area in the XY plane. For target marks of smaller sizes, such as text or a QR code, the scanning area of ​​the galvanometer module 500 can cover the target mark. At this time, the galvanometer module 500 needs to be moved, and the galvanometer motor inside the galvanometer module 500 does not need to move. The laser beam is deflected at a random angle by the acousto-optic deflector 300, and after being reflected by the first reflector and the second reflector, a light spot at a random position is generated in the scanning area of ​​the XY plane. It should be noted that the position path and scanning progress of the light spot landing point are planned in advance by the host computer, which can ensure that the position of each light spot landing point is not adjacent or overlapping, and that all light spot landing points can form a preset target mark.

[0064] In other application examples, the scanning area of ​​the galvanometer module 500 covers a part of the target mark on the transparent film, and step S400, based on the random position scanning method, laser marking the transparent film in the scanning area of ​​the galvanometer module 500 includes:

[0065] S420, based on the random position scanning method, laser marking is performed on the transparent film in the scanning area of ​​the galvanometer module 500 to complete the local marking of the target logo;

[0066] The galvanometer module 500 is moved to the next marking position, and based on the random position scanning method, the transparent film is laser marked in the scanning area of ​​the galvanometer module 500 until the marking of the target mark is completed.

[0067] For example, for a target mark with a larger size, the scanning area of ​​the galvanometer module 500 can only cover part of the target mark. In order to process a complete target mark, the target mark can be divided into multiple areas for scanning during the scanning position and path planning stage of the host computer. The size of each area is less than or equal to the scanning area of ​​the galvanometer module 500. In this way, the galvanometer module 500 can move to the first area for local scanning to complete the local marking of the target mark, and then move to the second area for local scanning to complete the local marking of the target mark, and so on, until the scanning of all areas is completed and the complete target mark is processed.

[0068] Step S100, placing a transparent film in a laser marking area, and then further comprising:

[0069] S110 , controlling the galvanometer module 500 to move to a marking processing position of the transparent film.

[0070] Exemplarily, in the initial state, the galvanometer module 500 is located at the initial position. When marking processing is required, the galvanometer module 500 is moved to the marking processing position through mechanisms such as an X-axis moving mechanism and a Y-axis moving mechanism to perform marking processing.

[0071] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A laser marking device, suitable for marking transparent films, characterized in that: include: A femtosecond laser (100), used for outputting a femtosecond laser beam; A beam expander (200), arranged at the laser output end of the femtosecond laser (100); an acousto-optic deflector (300), arranged at the laser emission end of the beam expander (200); A reflector module (400) is arranged at the laser emission end of the acousto-optic deflector (300). A galvanometer module (500) is arranged on the first side of the reflector module (400) and is located on the reflection light path, and a lens (700) is arranged at the laser emission end of the galvanometer module (500); A coaxial positioning camera (600) and the galvanometer module (500) are distributed on two opposite sides of the reflector module (400); The acousto-optic deflector (300) is used to deflect the femtosecond laser beam at a random angle, so as to generate light spots with random positions within the scanning area of ​​the galvanometer module (500) to perform laser marking on the transparent film.

2. The laser marking device according to claim 1, characterized in that: The femtosecond laser (100) is an infrared femtosecond laser, an ultraviolet femtosecond laser or a green femtosecond laser.

3. The laser marking device according to claim 1 or 2, characterized in that: The laser wavelength of the femtosecond laser (100) is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

4. The laser marking device according to claim 1 or 2, characterized in that: The beam expander (200) is an adjustable variable magnification beam expander.

5. A laser marking method, suitable for marking transparent films, characterized in that: include: Placing the transparent film in a laser marking area, wherein a galvanometer module (500) is arranged in the laser marking area; Outputting a femtosecond laser beam through a femtosecond laser (100), and performing beam expansion processing on the femtosecond laser beam through a beam expander (200); The femtosecond laser beam that has undergone beam expansion is deflected at a random angle by an acousto-optic deflector (300), and the femtosecond laser beam is output to the galvanometer module (500) by a reflector module (400), so as to generate light spot landing points at random positions within a scanning area of ​​the galvanometer module (500); Based on a random position scanning method, the transparent film is laser marked within a scanning area of ​​the galvanometer module (500).

6. The laser marking method according to claim 5, characterized in that: The femtosecond laser (100) is an infrared femtosecond laser, an ultraviolet femtosecond laser or a green femtosecond laser, and the femtosecond laser beam is outputted by the femtosecond laser (100), comprising: Outputting an infrared femtosecond laser beam through an infrared femtosecond laser; Alternatively, an ultraviolet femtosecond laser beam is outputted by an ultraviolet femtosecond laser; Alternatively, a green femtosecond laser beam is outputted by a green femtosecond laser.

7. The laser marking method according to claim 5 or 6, characterized in that: The laser wavelength of the femtosecond laser (100) is 1030 nanometers, and the minimum pulse width is 200 femtoseconds.

8. The laser marking method according to claim 5 or 6, characterized in that: The scanning area of ​​the galvanometer module (500) covers the target mark on the transparent film, and the laser marking of the transparent film in the scanning area of ​​the galvanometer module (500) based on the random position scanning method includes: Based on a random position scanning method, the transparent film is laser marked within the scanning area of ​​the galvanometer module (500) to complete the entire marking of the target logo.

9. The laser marking method according to claim 5 or 6, characterized in that: The scanning area of ​​the galvanometer module (500) covers a part of the target mark of the transparent film, and the laser marking of the transparent film in the scanning area of ​​the galvanometer module (500) based on the random position scanning method includes: Based on a random position scanning method, laser marking is performed on the transparent film within the scanning area of ​​the galvanometer module (500) to complete the local marking of the target mark; The galvanometer module (500) is moved to the next marking position, and based on a random position scanning method, the transparent film is laser marked within the scanning area of ​​the galvanometer module (500) until the marking of the target mark is completed.

10. The laser marking method according to claim 5, characterized in that: The step of placing the transparent film in the laser marking area further comprises: The galvanometer module (500) is controlled to move to a marking processing position of the transparent film.

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