Laser marking device and laser marking method

Abstract

The present invention comprises: a first beam splitter that splits a laser beam into a main beam and a sub-beam; a sub-beam scanning unit formed from a plurality of two-mirror pairs that cause the sub-beam to scan; a second beam splitter that transmits the main beam and reflects the sub-beam; a main beam scanning unit that causes a multi-beam formed from the main beam having passed through the second beam splitter and the sub-beam to scan across a printing target; and a control unit that controls the operations of the sub-beam scanning unit and the main beam scanning unit. The control unit controls the main beam and the sub-beam on the basis of the scanning direction of the multi-beam, which changes on the printing target, and controls the sub-beam scanning unit so that the main beam and the sub-beam are arranged side by side with respect to the changing scanning direction of the multi-beam.

Description

Laser marking device and laser marking method

[0001] The present invention relates to a laser marking device and a laser marking method.

[0002] A laser marking device scans a laser beam within a predetermined area using a galvanometer scanner or the like, and irradiates the laser beam onto the surface of the object to be marked, such as a part or product, and performs marking by foaming, condensing, carbonizing, coloring due to a chemical change, or peeling off the surface of the object to be marked.

[0003] For example, Patent Document 1 states that "multiple laser beams L1 etc. emitted from a semiconductor laser are converted into multiple beams at different angles by lenses 7 and 8, which are optical axis angle adjustment means, and these beams are reflected by X mirror 9 and Y mirror 10, which are each driven by a galvano scanner, to enter fθ lens 19a as laser beams L1a etc., and are focused at beam spot positions P1 etc. on workpiece 20 placed at the focal position of fθ lens 19a, thereby processing workpiece 20. Beam spot positions P1 etc. are scanned by the above two mirrors, and the distance between the beam spots is adjusted by the angle between the beams."

[0004] Japanese Patent Application Publication No. 11-156567

[0005] To increase the marking speed of laser marking, there are three methods: increasing the laser pulse energy to increase the print dot size, increasing the laser repetition frequency to increase the beam scanning speed, and using multiple beams to perform batch marking, as described in Patent Document 1. In addition to the complexity of the marking method, batch marking using multiple beams has the following problems.

[0006] When multiple laser beams are combined to generate a multibeam, or when a single laser beam is split into multiple beams and then combined to generate a multibeam, the multibeam cannot be rotated. This creates the problem of varying marking widths depending on the scanning direction of the multibeam. For example, as shown in FIG. 1A, consider a case in which a laser beam group LG consisting of two parallel laser beams L1 and L2 is marking an object with a marking width of "1" in a beam scanning direction D1. In this case, as shown in FIG. 1B, if the beam scanning direction is tilted from the beam scanning direction D1 to a beam scanning direction D2 diagonally downward to the right, the marking width of the laser beam group LG may change from "1" to "0.7". Furthermore, if the beam scanning direction is tilted in the same direction so that the laser beam group LG is aligned horizontally in the beam scanning direction D3, the marking width of the laser beam group LG may change from "0.7" to "0.5", as shown in FIG. 1C.

[0007] To solve this problem of different marking widths, it is necessary to rotate the multi-beams on the object to be marked, as shown in Fig. 2A. In Fig. 2A, of the two parallel laser beams L1 and L2 that make up the laser beam group, the laser beam L1 is positioned above the laser beam L2 due to the rotation. If the multi-beams can be rotated in this way, it is possible to always arrange the multi-beams perpendicular to the beam scanning direction, as shown in Fig. 2B, for example, so that the marking width can be kept constant and independent of the beam scanning direction.

[0008] On the other hand, another method for generating multiple beams is to use a multi-beam generating element such as a Wollaston prism or a Nomarski prism. In this case, the multi-beam can be rotated by rotating the multi-beam generating element, so the problem of the marking width varying depending on the scanning direction of the multi-beam does not occur. However, because the speed at which the multi-beam generating element rotates cannot keep up with the marking speed, it is difficult to achieve a high marking speed.

[0009] An object of the present invention is to provide a technique that can keep the beam width of a multi-beam constant and achieve high-speed marking, regardless of the beam scanning direction.

[0010] A laser marking device according to the present invention comprises a first beam splitter that splits laser light into a main beam and sub beams, a sub beam scanning unit consisting of a plurality of two mirror pairs that scans the sub beams, a second beam splitter that transmits the main beam and reflects the sub beams, a main beam scanning unit that scans a marking object with a multibeam consisting of the main beam and the sub beams that have passed through the second beam splitter, and a control unit that controls the operation of the sub beam scanning unit and the main beam scanning unit, wherein the control unit controls the main beam and the sub beams based on the scanning direction of the multibeam that changes on the marking object, and controls the sub beam scanning unit so that the main beam and the sub beams are aligned horizontally relative to the changing scanning direction of the multibeam.

[0011] The present invention aims to provide a technology that can maintain a constant beam width of a multi-beam regardless of the beam scanning direction and achieve high marking speed. Note that other problems, configurations, and effects will become clear from the following description of the preferred embodiment of the invention.

[0012] 10 is a diagram explaining that the marking width varies depending on the scanning direction of the multi-beam. FIG. 11 is a diagram explaining that the marking width varies depending on the scanning direction of the multi-beam. FIG. 12 is a diagram explaining that the marking width varies depending on the scanning direction of the multi-beam. FIG. 13 is a diagram explaining the state of marking when rotational operation of the multi-beam is possible. FIG. 14 is a diagram explaining the state of marking when rotational operation of the multi-beam is possible. FIG. 15 is a diagram showing an example of the configuration of a laser marking device (Example 1). FIG. 16 is a diagram showing an example of the three-dimensional configuration of the laser marking device shown in FIG. 3. FIG. 17 is an explanatory diagram for marking an object to be marked with a laser beam group that is a multi-beam composed of two parallel laser beams with respect to a changing beam scanning direction of the multi-beam. FIG. 18 is a diagram showing an example of control data for a control device to control a galvanometer scanner by following the changing beam scanning direction of the multi-beam. FIG. 19 is a diagram showing an example of a schematic configuration of a computer. FIG. 19 is a flowchart showing an example of a processing procedure for multi-beam scanning processing. FIG. 19 is a diagram showing an example of the configuration of a laser marking device (Example 2). FIG. 19 is a diagram showing an example of the configuration of a laser marking device (Example 3). FIG. 19 is a diagram showing an example of a secondary galvanometer mirror having a mirror with a portion cut out in order to control the secondary beam. FIG. 19 is a diagram showing an example of a configuration in which a polarizing beam splitter is used instead of the beam splitter shown in FIG.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The examples are illustrative for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0014] In addition, when there are multiple components having the same or similar functions, they may be described by using the same reference numeral with different subscripts, or when there is no need to distinguish between these multiple components, the subscripts may be omitted.

[0015] In the embodiments, processing performed by executing a program may be described. Here, a computer executes the program using a processor (e.g., a CPU or a GPU) and performs processing defined by the program using storage resources (e.g., memory) and interface devices (e.g., communication ports). Therefore, the entity performing the processing by executing the program may be the processor. Similarly, the entity performing the processing by executing the program may be a controller, device, system, computer, or node having a processor. The entity performing the processing by executing the program may be any computing unit, and may include a dedicated circuit that performs specific processing. Here, the dedicated circuit may be, for example, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a CPLD (Complex Programmable Logic Device), or the like.

[0016] A program may be installed on a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and storage resources for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In addition, in the embodiments, two or more programs may be realized as one program, or one program may be realized as two or more programs.

[0017] In this embodiment, the case of two-beam marking will be described using Figures 2, 3, 4, and 5. Figure 3 is a diagram showing an example of the configuration of the laser marking device in this embodiment. Also, Figure 4 is a diagram showing an example of the three-dimensional configuration of the laser marking device 1000 shown in Figure 3.

[0018] As shown in FIG. 3 , the laser marking device 1000 of this embodiment includes a splitting beam splitter 2 that splits a laser beam 1 emitted from a light source into a main beam 18 and sub beams 19, a mirror 3 that reflects the sub beam 19, a sub galvanometer scanner 4 that controls the relative position of the sub beam 19 with respect to the main beam, a main galvanometer scanner 5 that scans a multibeam formed by combining the main beam 18 and the sub beams 19, a condenser lens 6 that condenses the multibeam scanned by the main galvanometer scanner 5, a control device 7 that controls the main galvanometer scanner 5 and the sub galvanometer scanner 4, and a combining beam splitter 21 that combines the main beam 18 with the sub beams 19 whose relative positions are controlled by the sub galvanometer scanner 4. The multibeams condensed by the condenser lens 6 are irradiated onto the marking target object. While the following describes an example in which there is one sub beam 19, the same applies to cases in which there are two or more sub beams 19.

[0019] Next, the operation of the laser marking device 1000 will be described. First, a laser beam 1 emitted from a light source is split into a main beam 18 and a sub beam 19 by a beam splitter 2. The sub beam 19 is reflected by a mirror 3 and then passes through a sub galvanometer scanner 4 consisting of two mirrors before entering a combining beam splitter 21. In FIG. 4 , the direction of the sub beam 19 reflected by the mirror 3 is controlled by a sub galvanometer mirror 8 for scanning the beam in the X direction, and then further controlled by a sub galvanometer mirror 9 for scanning the beam in the Y direction. The sub beam 19 then passes through these sub galvanometer mirrors that make up the sub galvanometer scanner 4 and enters the combining beam splitter 21, where it is combined with the main beam 18 reflected by the two mirrors 3. The combined main beam 18 and sub-beam 19 pass through a main galvanometer scanner 5, which is composed of a main galvanometer mirror 10 for scanning the beam in the X direction and a main galvanometer mirror 11 for scanning the beam in the Y direction, and are focused by a focusing lens 6 and irradiated onto the marking object 12.

[0020] The position of the sub beam 19 relative to the main beam is controlled by the sub galvanometer scanner 4, as shown in Fig. 2A. The position control method is as follows. As shown in Fig. 2B, the main beam 18 and the sub beam 19 are controlled so that their alignment is perpendicular to the scanning direction of the main beam 18. Such beam scanning control is performed by the control device 7 of the galvanometer scanner.

[0021] For example, consider a case where the control device 7 controls the sub-galvanometer scanner 4 to mark the number "0" on the marking object 12 with a laser beam group that is a multi-beam consisting of two parallel laser beams in the changing beam scanning direction. In the following, numbers are exemplified as marking information to be marked on the marking object 12, but various information such as alphabets, symbols, and codes may be used as the marking information.

[0022] FIG. 5 is an explanatory diagram for marking an object 12 with a laser beam group 5011, which is a multibeam consisting of two parallel laser beams 501A and 501B, aligned with the changing beam scanning direction of the multibeam. In FIG. 5, two locations of the numeral "0" are used as an example to explain marking by changing the beam scanning direction of the multibeam. However, this is not limited to these locations, and any location may be similarly considered. Furthermore, the numeral "0" in this example is marked collectively with a predetermined marking width (e.g., 1 mm) by the multibeam following the beam scanning direction. For example, at position 501, the beam scanning direction is a downward direction 5012a, while at position 502, the beam scanning direction is a diagonally downward right direction 5012b. The control device 7 controls the galvanometer mirror so that the spot positions of each beam constituting the multibeam always remain aligned side by side with respect to the changing beam scanning direction.

[0023] The control device 7 calculates the coordinates of the spot positions of the laser beams 501A and 501B that constitute the number "0" on the marking object 12. For example, the control device 7 calculates the coordinates of the spot positions of the laser beams 501A and 501B at position 501 among a group of multiple laser beams that constitute the number "0" to be marked at a predetermined position on the marking object 12. The coordinates can be expressed, for example, as the spot positions of the laser beam 501A and the laser beam 501B on an xy plane that includes the origin position O of the marking object 12. The control device 7 similarly calculates the coordinates of the spot positions of the laser beams 501A and 501B at position 502 and other positions. By calculating the coordinates in this way, the spot positions on the marking object 12 of all of the multiple beams that constitute the number "0" that is the marking information are calculated.

[0024] Furthermore, the control device 7 determines the marking order at the calculated spot positions, and calculates the relative position of the sub beam 19 with respect to the main beam 18 so that the spot position of the main beam 18 and the spot position of the sub beam 19 are aligned horizontally in the beam scanning direction at each spot position. In accordance with the marking order, the control device 7 reads the beam scanning direction for marking the number "0" which is predetermined marking information, the calculated spot position of the main beam 18, and the relative spot position of the sub beam 19 at the spot position of the main beam 18, and controls the galvanometer mirror at each spot position in the marking order.

[0025] Fig. 6 is a diagram showing an example of control data used by the control device 7 to control the galvanometer scanner in accordance with the changing beam scanning direction of the multi-beam. As shown in Fig. 6, the control data 601 stores, as beam information, the beam type (main beam, sub-beam) indicating whether it is the main beam 18 or the sub-beam 19, the beam scanning direction of the multi-beam, the angle (sub-beam angle) of the galvanometer mirror of the sub-beam 19 controlled to follow the beam scanning direction, and the order in which the marking information is to be applied (marking order), in association with the spot positions (P1, ..., Pn ...) constituting the marking information.

[0026] 6 shows, for example, that at spot position P1 of the first multi-beam having a marking order of "1," the spot position of the main beam 18 is "m(x1, y1)," the spot position of the sub-beam 19 is "s(x11, y11)," and the beam scanning direction of the multi-beam is "D1." It also shows that, in order to make the spot position follow the beam scanning direction of the multi-beam, when marking at the next spot position, the sub-galvanometer mirrors 8 and 9 of the galvanometer scanner 4 of the sub-beam 19 are changed by an angle of "Δp1." The process of controlling the galvanometer scanner using control data 601 to follow the changing beam scanning direction of the multi-beam will be described later with reference to a flowchart.

[0027] The control device 7 can be realized, for example, by a general computer 201, as shown in FIG. 7 (schematic diagram of a computer), which includes a CPU 202, a memory 203, an external storage device 204 such as an HDD (Hard Disk Drive), an external medium output device 207 that reads and writes information from and to a portable storage medium such as a CD (Compact Disk) or USB memory, an input device 206 such as a keyboard or a mouse, an output device 205 such as a display, and a network communication device 208 such as a NIC (Network Interface Card) for connecting to a communication network.

[0028] Furthermore, various data stored in the control device 7 or used for processing can be realized by the CPU 202 reading and using the data from the memory 203 or the external storage device 204. Furthermore, the functions of the control device 7 can be realized by the CPU 202 loading a predetermined program stored in the external storage device 204 into the memory 203 and executing it.

[0029] The above-mentioned predetermined program may be stored (downloaded) into the external storage device 204 from a storage medium via the external medium output device 207 or from a network via the network communication device 208, and then loaded onto the memory 203 and executed by the CPU 202. Alternatively, the program may be directly loaded onto the memory 203 from a storage medium via the external medium output device 207 or from a network via the network communication device 208, and executed by the CPU 202. Next, the process (multi-beam scanning process) performed by the laser marking device in this embodiment will be described.

[0030] 8 is a flowchart showing an example of a processing procedure for multi-beam scanning processing. As shown in FIG. 8 , first, the control device 7 reads the coordinates of the marking object 12 set at a predetermined position and information about the size and configuration of marking information (e.g., the number "0" constituting the serial number) to be marked on the marking object 12, which are stored in advance in a storage medium such as a memory, and calculates the spot positions of the main beam 18 and the sub beams 19 (S801). For example, the control device 7 reads the coordinates of the vertices of the four corners of the marking object 12, the vertical and horizontal sizes of the number "0," the spot positions of the multi-beams constituting the number "0," and the spot positions of the main beam 18 and the sub beams 19 constituting the multi-beams, creates coordinate data of the marking information, and writes the coordinates of the "main beam" and the "sub beam" in the control data 601 shown in FIG. 6 .

[0031] Next, the control device 7 reads the coordinate data written in S801, calculates the beam scanning direction of the multi-beam, determines the marking order, and calculates control information for the sub-galvano scanners 4 for controlling the sub-beams 19 (S802). For example, the control device 7 calculates the midpoint between the spot position of the main beam 18 and the spot position of the sub-beams 19 as the spot position of the multi-beam, and calculates the beam scanning direction "D1" of the multi-beam in the coordinates of the marking object 12 from the line segment connecting the spot positions of adjacent multi-beams. If there are two or more sub-beams 19, for example, the beam scanning direction "D1" is the midpoint between the spot position of the main beam 18 and the spot position of the sub-beam 19 at the end opposite to the main beam 18 among the multiple sub-beams 19.

[0032] The control device 7 determines the marking order in the order in which the above calculations were performed, and writes this information into "beam scanning direction" and "marking order" in the control data 601 shown in Fig. 6. Furthermore, the control device 7 calculates an angle Δp1 for scanning the secondary galvanometer mirrors 8 and 9 of the secondary galvanometer scanner 4 from the rate of change of the beam scanning direction of the multi-beams at the spot position next to the spot position in the written "beam scanning direction" (the degree of change in the tilt of the beam scanning direction of the multi-beams) so that the spot position of the main beam 18 and the spot positions of the secondary beams 19 are aligned parallel to each other and substantially perpendicular to the beam scanning direction (positions where the main beam 18 and the secondary beams 19 are aligned horizontally in the scanning direction of the multi-beams), and writes this into "secondary beam angle" in the control data 601 shown in Fig. 6. When the processing of S802 is completed, the control data 601 shown in Fig. 6 is created.

[0033] The control device 7 reads out the control data 601 created in S802, and creates mirror control data for controlling the main galvanometer mirrors 10 and 11 that constitute the main galvanometer scanner 5 that controls the main beam 18, and the secondary galvanometer mirrors 8 and 9 that constitute the secondary galvanometer scanner 4 that controls the secondary beam 19 (S803). For example, the control device 7 converts the control data 601 into a predetermined format that can be controlled by actuators for driving the main galvanometer mirrors 10 and 11 and the secondary galvanometer mirrors 8 and 9 described above, and outputs the converted data as mirror control data.

[0034] The control device 7 reads out the mirror control data for each galvanometer mirror at each spot position of the main beam 18 and the sub beams 19, created in S803, in accordance with the marking order, and drives the actuator for controlling the main beam 18 to scan the combined beam of the main beam and the sub beams (S804A).

[0035] Furthermore, similarly to S804A, the control device 7 reads out the mirror control data in accordance with the marking order, and drives the actuator for controlling the sub beam 19 to scan the sub beam 19 so that the arrangement of the multibeam consisting of the main beam 18 and the sub beam 19 is horizontal in the scanning direction of the multibeam (S804B). Specifically, the control device 7 changes the angles of the sub galvanometer mirrors 8 and 9 that scan the sub beam 19 relative to the main galvanometer mirrors 10 and 11 that scan the main beam 18 by the "sub beam angle" written as the mirror control data, so that the spot positions of the sub beam 19 and the main beam 18 are horizontal in the changing scanning direction of the multibeam.

[0036] Example 2 will be described with reference to Fig. 9. Example 2 differs from Example 1 in that a polarizing beam splitter 13 is used instead of the beam splitter 2. This method can reduce the loss of laser power compared to Example 1.

[0037] FIG. 9 shows an example of the configuration of a laser marking device in this embodiment. As shown in FIG. 9, in the laser marking device in this embodiment, the polarization direction of laser beam 1 (assumed to be S-polarized in FIG. 9) is tilted by 45 degrees by a polarizing beam splitter and made incident on a splitting polarizing beam splitter 14. In this example, a half-wave plate is used as the polarizing beam splitter 13. Splitting polarizing beam splitter 14 splits laser beam 1, whose polarization direction has been tilted by 45 degrees by polarizing beam splitter 13, into a P-polarized beam 16 and an S-polarized beam 15 of equal intensity. P-polarized beam 16 is then reflected by two mirrors 3 and incident on a combining polarizing beam splitter 22.

[0038] On the other hand, S-polarized beam 15 is converted into a P-polarized beam when reflected by mirror 3 and secondary galvanometer mirror 8. Therefore, the converted P-polarized beam is converted back into an S-polarized beam by polarizing beam splitter 13, reflected by secondary galvanometer mirror 9, and made to enter combining polarizing beam splitter 22, after which it is combined with the above-mentioned P-polarized beam. The combined P-polarized beam 16 and S-polarized beam 15 pass through main galvanometer mirrors 10 and 11, and are focused on marking object 12 by focusing lens 6.

[0039] In this embodiment, by performing processing similar to the multi-beam scanning processing (FIG. 8) described in embodiment 1, it is possible to keep the beam width of the multi-beam constant and achieve faster marking speeds, regardless of the beam scanning direction.

[0040] Example 3 will be described with reference to FIG. 10 . Example 3 is an example in which the number of sub beams is two or more. FIG. 10 shows an example of the configuration of a laser marking device in this example. In FIG. 10 , sub beam 19 separated by beam splitter 2 is further separated by beam splitter 2a into sub beams 191 and 192. Sub beam 192 is further separated by beam splitter 2b into sub beams 193 and 194. Subsequently, the sub beams are separated by beam splitter 2 in this manner.

[0041] Thus, when the number of sub beams is two or more, when each sub beam is incident on the combining beam splitter 22 for combining the main beam and the sub beams, the sub galvanometer scanners (e.g., sub galvanometer scanners 4a and 4b) scanning other sub beams become an obstacle, and some of the sub beams re-split from the beam splitters for splitting the sub beams, such as beam splitters 2a and 2b, cannot propagate 1001 to the combining beam splitter 22. To solve this problem, as shown in Figure 11, for example, a sub galvanometer mirror 17 having a partially cut mirror is used to control the re-split sub beams in the Y direction. In Figure 11, the portion 1101 indicated by the dotted line is cut, and the re-split sub beams are incident on the combining beam splitter 22 without interference.

[0042] Furthermore, as shown in Figure 12, a configuration diagram using a polarizing beam splitter instead of the beam splitter 2 shown in Figure 10 is shown. By using a half-wave plate as the polarizing beam splitter 13 before each sub-galvano scanner 4, the polarization is converted into a beam that can be multiplexed with the main beam by the multiplexing polarizing beam splitter 22. In Figure 12, the sub-beam 19 separated by the splitting polarizing beam splitter 14 via the half-wave plate of the polarizing beam splitter 13 is further separated into sub-beams 191 and 192 by the beam splitter 2a, as in the case of Figure 10, and the sub-beam 192 is then separated into sub-beams 193 and 194 by the beam splitter 2b. Thereafter, the sub-beams are separated by the beam splitter 2 in this way, but the sub-beams that are not re-separated (e.g., sub-beams 191 and 193) are incident on each sub-galvano scanner 4 via the half-wave plate of the polarizing beam splitter 13. 10, each sub-galvanometer scanner 4 transmits the beam to a beam combining splitter 22. The sub-galvanometer mirror 17 in this case is a mirror with a part cut out, as shown in FIG.

[0043] In this embodiment, by performing processing similar to the multi-beam scanning processing (FIG. 8) described in embodiment 1, it is possible to keep the beam width of the multi-beam constant and achieve faster marking speeds, regardless of the beam scanning direction.

[0044] Each embodiment has been described above. In the first embodiment, as described with reference to FIGS. 3-5 etc., there is a first beam splitter (for example, beam splitter 2) that splits a laser beam (for example, laser beam 1) into a main beam (for example, main beam 18) and sub beams (for example, sub beam 19), a sub beam scanning unit (for example, sub galvanometer scanner 4, sub galvanometer mirrors 8, 9) that scans the sub beams, a second beam splitter (for example, beam combining beam splitter 21) that transmits the main beam and reflects the sub beams, and a beam splitter (for example, beam combining beam splitter 22) that splits the laser beam (for example, laser beam 1) into a main beam (for example, main beam 18) and sub beams (for example, sub beam 19). The marking apparatus includes a main beam scanning unit (e.g., a main galvanometer scanner 5, main galvanometer mirrors 10 and 11) that scans a multi-beam consisting of the main beam and the sub-beams that have passed through the main beam and the sub-beams onto a printing target (e.g., a marking target 12), and a control unit (e.g., a control device 7) that controls the operation of the sub-beam scanning unit and the main beam scanning unit, and the control unit controls the main beam and the sub-beams based on the scanning direction of the multi-beams that changes on the printing target, and controls the sub-beam scanning unit so that the main beam and the sub-beams are aligned horizontally with respect to the changing scanning direction of the multi-beam. With this configuration, the beam width of the multi-beams can be kept constant at all times without being affected by various changing beam scanning directions, making it possible to perform batch marking with multiple beams, thereby achieving faster marking speeds than before.

[0045] 9 and the like, the first beam splitter is configured as a polarizing beam splitter, which can transmit all P-polarized light and reflect all S-polarized light, or can reflect all P-polarized light and transmit all S-polarized light, thereby transmitting the beam energy to the beam spot without waste.

[0046] 9, the polarizing beam splitter may be configured as a half-wave plate, which can rotate the polarization direction of linearly polarized light.

[0047] As described using Example 3, FIG. 10 , etc., the first beam splitter (e.g., beam splitters 2, 2a, 2b) splits the laser light into a main beam and a plurality of sub-beams, the sub-beam scanning unit (sub-galvano scanners 4, 4a, 4b) scans the plurality of sub-beams, the second beam splitter (e.g., beam combining beam splitter 21) transmits the main beam and reflects the plurality of sub-beams, the main beam scanning unit (e.g., main galvano scanner 5) scans a printing target with a multi-beam consisting of the main beam and the plurality of sub-beams that have passed through the second beam splitter, the control unit controls the main beam and the plurality of sub-beams based on the scanning direction of the multi-beam that changes on the printing target, and controls the sub-beam scanning unit so that the main beam and the plurality of sub-beams are aligned horizontally with respect to the changing scanning direction of the multi-beam. As a result, even for a multi-beam having two or more sub-beams 19, the beam width of the multi-beam can always be kept constant without being affected by various changing beam scanning directions, and batch marking with multiple beams is possible, thereby enabling faster marking speeds than before.

[0048] 11 and the like, the sub-beam scanning unit (for example, the sub-galvano scanner 17) has a mirror that is partially cut out to transmit other sub-beams among the plurality of sub-beams, thereby ensuring that the other sub-beams can be transmitted.

[0049] 12 and the like, the laser marking device is provided with a half-wave plate (e.g., half-wave plate 13) between the first beam splitter that splits the beam into the plurality of sub-beams and each of the sub-beam scanning units that scans the plurality of sub-beams, thereby rotating the polarization direction of linearly polarized light for the split sub-beams.

[0050] The present invention is not limited to the above-described embodiments as they are, and in the implementation stage, the components can be modified and embodied within the scope of the gist of the present invention, or multiple components disclosed in the above-described embodiments can be appropriately combined.

[0051] 1: Laser beam 2: Demultiplexing beam splitter 3: Mirror 4: Auxiliary galvanometer scanner 5: Main galvanometer scanner 6: Condenser lens 7: Control device 8: Auxiliary galvanometer mirror (X direction) 9: Auxiliary galvanometer mirror (Y direction) 10: Main galvanometer mirror (X direction) 11: Main galvanometer mirror (Y direction) 12: Marking object 13: Polarizing beam splitter (half-wave plate) 14: Demultiplexing polarizing beam splitter 15: S-polarized light 16: P-polarized light 17: Auxiliary galvanometer scanner (Example 3) 18: Auxiliary beam 19: Main beam 20: Beam scanning direction by main beam 21: Combining beam splitter 22: Combining polarizing beam splitter

Claims

1. A laser marking device comprising: a first beam splitter that splits laser light into a main beam and sub beams; a sub beam scanning unit consisting of a plurality of two mirror pairs that scans the sub beams; a second beam splitter that transmits the main beam and reflects the sub beams; a main beam scanning unit that scans a marking object with a multi-beam consisting of the main beam and the sub beams that have passed through the second beam splitter; and a control unit that controls the operation of the sub beam scanning unit and the main beam scanning unit, wherein the control unit controls the main beam and the sub beams based on the scanning direction of the multi-beam that changes on the marking object, and controls the sub beam scanning unit so that the main beam and the sub beams are aligned horizontally relative to the changing scanning direction of the multi-beam.

2. The laser marking device according to claim 1, wherein the first beam splitter is a polarizing beam splitter.

3. The laser marking device according to claim 2, wherein the polarizing beam splitter is a half-wave plate.

4. The laser marking device according to claim 1, wherein: the first beam splitter splits the laser light into a main beam and multiple sub-beams; the sub-beam scanning unit scans the multiple sub-beams; the second beam splitter transmits the main beam and reflects the multiple sub-beams; the main beam scanning unit scans a multi-beam consisting of the main beam and the multiple sub-beams that have passed through the second beam splitter, onto the object to be marked; and the control unit controls the main beam and the multiple sub-beams based on the scanning direction of the multi-beam that changes on the object to be marked, and controls the sub-beam scanning unit so that the main beam and the multiple sub-beams are aligned horizontally relative to the changing scanning direction of the multi-beam.

5. The laser marking device according to claim 4, wherein the sub-beam scanning unit has a mirror that is partially cut to allow other sub-beams of the plurality of sub-beams to pass through.

6. The laser marking device according to claim 4, characterized in that a half-wave plate is provided between the first beam splitter that splits the laser beam into the plurality of sub-beams and each of the sub-beam scanning units that scans the plurality of sub-beams.

7. A laser marking method comprising: splitting laser light into a main beam and sub beams by a first beam splitter; scanning the sub beams by a sub beam scanning unit consisting of two or more pairs of mirrors; transmitting the main beam and reflecting the sub beams by a second beam splitter; scanning a multi-beam consisting of the main beam and the sub beams that have passed through the second beam splitter onto a marking target by a main beam scanning unit; controlling the main beam and the sub beams by a control unit based on the scanning direction of the multi-beam that changes on the marking target, and controlling the sub beam scanning unit so that the main beam and the sub beams are aligned horizontally relative to the changing scanning direction of the multi-beam.

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