Laser irradiation method, laser irradiation device, laser marking device and molding device

Abstract

To achieve laser output effective utilization and productivity improvement in laser beam raster scanning.SOLUTION: A laser irradiation method, which uses a first deflector (AOD20) and a second deflector (galvano-scanner 30) that deflects and scans laser beam and irradiates a laser irradiation object with the laser beam deflected by the first deflector by raster scanning with the second deflector, deflects the laser beam, which is moved to a non-irradiation region of the laser irradiation object by raster scanning, by the first deflector so as to radiate an unirradiated area separated from the non-irradiation area.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a laser irradiation method, a laser irradiation device, a laser marking device, and a modeling device in which a laser beam is deflected and scanned by a plurality of deflectors. [Background technology]

[0002] Patent Document 1 (Patent Publication No. 4108294) discloses a laser marking method in which a laser beam is raster scanned or vector scanned onto a marking object to mark the object. Raster scanning can increase the scanning speed (marking speed), but the laser beam is turned off for non-marking pixels, resulting in unnecessary scanning, so there is room for improvement from the viewpoints of effective use of laser output and improved productivity. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention has been made in view of the above circumstances, and an object of the present invention is to effectively utilize laser output and improve productivity in raster scanning of laser light. [Means for solving the problem]

[0004] In order to solve the above problems, the laser irradiation method of the present invention uses a first deflector and a second deflector for deflectively scanning laser light, and irradiates the laser light deflected by the first deflector onto an object to be laser irradiated by raster scanning using the second deflector, characterized in that the laser light moving to a non-irradiated area of ​​the object to be laser irradiated by the raster scanning is deflected by the first deflector so as to be irradiated onto an unirradiated area spaced from the non-irradiated area. Effect of the Invention

[0005] According to the present invention, it is possible to effectively utilize the laser output and improve the productivity in raster scanning of the laser light. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic plan view of a laser marking device according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a flow diagram of marking using laser light. [Diagram 3] FIG. 1 is a diagram showing the raster scanning trajectory of a galvanometer scanner and the deflection direction of an acousto-optic deflector (AOD). [Figure 4] FIG. 1A is a diagram showing an image pattern to be marked, FIG. 1B is a diagram showing a conventional marking method for marking the image pattern, and FIG. 1C and FIG. 1D are diagrams showing the marking method of the present embodiment. [Diagram 5] FIG. 13A is a diagram showing another image pattern to be marked, and FIGS. 13B and 13C are diagrams showing the marking method of this embodiment for marking the image pattern. [Figure 6] 3A and 3B are a schematic plan view and a schematic side view, respectively, of a laser marking device according to another embodiment of the present invention. [Figure 7] FIG. 13(a) is a diagram showing yet another image pattern to be marked, and (b) is a diagram showing the marking method of this embodiment for marking the image pattern. [Figure 8] FIG. 8 is a flow diagram of the marking in FIG. 7(b). [Figure 9] FIG. 7(b) is a diagram showing the marking method of the present embodiment in which two acousto-optic deflectors (AODs) are used to mark the image pattern of FIG. 7(a). [Figure 10] 8A to 8C are diagrams showing the marking method of the present embodiment in which the raster scanning range is expanded in the y direction to mark the image pattern of FIG. 7A. [Figure 11] FIG. 2 is a diagram for explaining a deflection angle θ by an acousto-optic deflector (AOD). [Figure 12A] FIG. 13 is a diagram showing an image pattern to be marked together with the irradiation density of laser light. [Figure 12B] 12B is a diagram in which the scanning trajectory of the laser light is added to FIG. 12A. [Figure 13]1A to 1D are diagrams illustrating examples (a) to (d) of deflecting a laser beam by changing the deflection angle θ of an acousto-optic deflector (AOD). [Figure 14] 13A and 13B are diagrams illustrating a marking method in which positional deviation of the marking is permitted. [Figure 15] FIG. 13 is a diagram for explaining an increase in marking speed, in which (a) is a diagram for explaining an image pattern to be marked, and (b) is a diagram for explaining a high-speed marking method. [Figure 16] 11A and 11B are diagrams illustrating multiple irradiations of laser light when the main scanning speed is accelerated or decelerated. [Figure 17] FIG. 13 is a diagram showing a method of marking two pixels when passing one pixel. [Figure 18] FIG. 2 is a diagram for explaining the beam diameter of a sound wave traveling through an acousto-optic deflector (AOD). [Figure 19] FIG. 2 is a block diagram of a laser irradiation control unit and a laser scanning control unit. [Figure 20] FIG. 1 is a diagram illustrating a method for controlling an acousto-optic deflector (AOD). [Figure 21] FIG. 1 illustrates a powder bed fusion apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] ● Laser marking device Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a plan view of a laser marking device 100 according to an embodiment of the present invention. This laser marking device 100 includes a laser oscillator 10 as a laser light source, an acousto-optic deflector 20 as a first deflector or first scanning means, a galvano scanner 30 as a second deflector or second scanning means, and an fθ lens 40. Hereinafter, the acousto-optic deflector is referred to as an "AOD" (Acousto-Optic Deflector).

[0008] The AOD 20 includes a piezoelectric transducer coupled to the crystal and a radio frequency (RF) driver that drives the piezoelectric transducer such that the RF driver generates RF frequency acoustic waves within the crystal, e.g., acoustic waves in a frequency range between about 50 MHz and about 1500 MHz.

[0009] The incident laser light is diffracted by the acoustic waves generated in the crystal in proportion to the RF frequency, and a portion of the input beam power is deflected as first order light (diffracted light).

[0010] A laser beam emitted from a light source (laser oscillator 10) is deflected by the AOD 20, and the first-order light (diffracted light) thereof is incident on the galvano scanner 30. The laser beam incident on the galvano scanner 30 is raster-scanned by the galvano scanner 30.

[0011] The raster scanned laser light is incident on an fθ lens 40, which is a condenser lens. The laser light emitted from the fθ lens 40 is irradiated onto a marking object 50, and forms a marking on the surface (or inside) of the marking object 50. The marking object 50 is, for example, a resin object such as a PET bottle.

[0012] The fθ lens 40 is configured to focus the laser light scanned by the galvano scanner 30 onto the marking object 50. For example, the fθ lens 40 is configured to scan the laser light scanned by the galvano scanner 30 at a predetermined angle on the imaging surface of the marking object 50 at a predetermined pitch.

[0013] FIG. 2 shows a flow from when light (laser light) emitted from a light source (laser oscillator 10) is incident on a marking target 50 to when the laser irradiation position is marked. The light emitted from the light source at S1 is incident on the AOD 20 at S2, and a part of the light is diffracted at an angle according to the wavelength of the incident light, the sound speed of the AOD 20 crystal, and the RF signal frequency applied from the RF driver connected to the AOD 20 to become first-order light (diffracted light). The component of the light incident on the AOD 20 that is not diffracted travels straight as zero-order light (transmitted light) as shown in FIG. 1 and is blocked (terminated) by the beam damper 21. In FIG. 1, the zero-order light is blocked by the beam damper 21, but in cases where the power of the zero-order light is so low that the marking target 50 is not marked even when the zero-order light is incident on the marking target 50, the zero-order light does not necessarily need to be blocked.

[0014] The primary light is incident on the galvanometer scanner 30 and is deflected by the galvanometer scanner 30 (S3). The light deflected by the galvanometer scanner 30 is focused by the fθ lens 40 at a marking position on the marking object 50 that corresponds to the angle of incidence on the fθ lens (S4).

[0015] The surface of the marking portion on the marking object 50 irradiated with the laser is scraped or modified by the laser, thereby forming a visible marking (S5).

[0016] Since the light (first-order light) diffracted by the AOD 20 is scanned by the galvanometer scanner 30, the laser irradiation position on the marking object 50 is controlled by two means, the AOD 20 and the galvanometer scanner 30. If necessary, a beam diameter conversion element, a beam profile shaping element, a wave plate, etc. can be provided before or after the AOD 20 of the laser marking device 100 in FIG.

[0017] A pulsed laser having a wavelength of, for example, 355 nm, 532 nm, or 1064 nm can be used as the light source of the laser oscillator 10. A pulsed laser is a type of laser whose laser output varies with time. The pulse width is, for example, from several tens of fs to several hundreds of ns.

[0018] Instead of a pulsed laser, a CW (Continuous Wave) oscillation laser may be used by switching as the light source of the laser oscillator 10. A CW oscillation laser is a type of laser in which the laser output does not change over time and remains at a constant value.

[0019] The AOD 20 is driven by an RF driver, and the first-order diffracted light propagates at an angle proportional to the RF frequency. Therefore, the deflection angle of the AOD 20 can be controlled by controlling the RF frequency.

[0020] The deflection control by the AOD 20 does not have inertia, unlike the galvanometer scanner 30 or the polygon scanner. For this reason, the deflection control by the AOD 20 can deflect the laser light at high speed (for example, in a time of 5 us or less).

[0021] Furthermore, the deflection control by the AOD20 can provide a different deflection angle for each pulse even for a pulse laser with a high repetition rate (e.g., 200 kHz). In this embodiment, the AOD20 is used as the deflection means, but the deflection means is not limited to this. The deflection means can be configured with any deflection means having a desired response speed. As other deflection means that can be substituted for the AOD20, for example, an electro-optic deflector (EOD) or a mirror optical deflector using a piezoelectric element (piezo element) capable of high speed response may be used.

[0022] 3, the angle between the deflection direction (indicated by a dashed line) of the AOD 20 and the sub-scanning direction (+x direction) of the galvano scanner 30 is defined as θ (deflection angle). The direction of rotation from +x to +y (clockwise) is defined as positive.

[0023] ● Marking of 4 x 5 pixel images A specific marking method and an embodiment that shortens the time required for marking will be described using the example of a simple image pattern in Fig. 4. Consider marking a 4 x 5 pixel image as shown in Fig. 4(a). Here, for simplicity, a small image size of 4 x 5 pixels is used, but the actual image size may be, for example, several hundred pixels x several hundred pixels, or even larger.

[0024] For convenience, the x coordinate of the mth column from the left is m, and the y coordinate of the nth row from the top is n, so the coordinates (x,y)=(m,n) are simply written as (m,n). The pixels filled with light ink are marking pixels (irradiated areas). The white pixels are non-marking pixels (non-irradiated areas).

[0025] ● Conventional marking 4(b) shows the relationship between the scanning trajectory of the laser light and the laser irradiation position in general raster scanning as a comparative example. The main scanning direction of the galvano scanner 30 is y, the sub-scanning direction is x, and the sub-scanning direction is from -x to +x.

[0026] Main scanning refers to scanning in the row direction (±y direction), and sub-scanning refers to moving to the next row. In general raster scanning, all main scan rows that have at least one marking pixel are scanned. Therefore, in the example of Figure 4(b), marking of the marking pixel is completed after four main scans.

[0027] For simplicity, unless otherwise specified, the laser light source is a pulsed laser, and one pixel is marked by one pulse irradiation.

[0028] In addition, the laser irradiation pitch (pitch [m] = galvano main scanning speed [m / s] / repetition frequency [1 / s]) calculated from the galvano main scanning speed and the laser repetition frequency is assumed to match the pixel size. However, even if multiple pulse irradiations are required to mark one pixel, or if the light source is not a pulse laser, or if the laser irradiation pitch and the pixel size do not necessarily match, the present invention will have the same effect.

[0029] Marking in this embodiment An example of the marking method of this embodiment is shown in Fig. 4(c). In Fig. 4(c), "scanning trajectory of laser light by galvano scanner" means the scanning trajectory of laser light generated by raster scanning of galvano scanner 30 when the deflection angle of AOD 20 is kept at a certain reference value.

[0030] The deflection direction of the laser light by the AOD 20 is set to θ=0 (+x direction). The x and y coordinates of the scanning trajectory of the laser light by the galvano scanner 30 at a certain point in time are set to x0 and y0, respectively.

[0031] The deviations of the x and y coordinates of the laser light due to deflection angle control of the AOD 20 are respectively Δx and Δy (unit: pixels) as relative values ​​from x0 and y0. For example, when x0=2 and Δx=1, the x coordinate of the irradiation position of the laser light is 3. The maximum and minimum values ​​of Δx are respectively Δx_max and Δx_min, and the maximum and minimum values ​​of Δy are respectively Δy_max and Δy_min.

[0032] The scannable range of the AOD 20 on the marking object 50 (on the marking surface) is determined by the scanning angle of the AOD 20 and the fθ lens 40. The possible ranges of Δx and Δy are determined by the relationship between the scannable range of the AOD 20 and the pixel size.

[0033] For example, in this embodiment, the fθ lens focal length is 200 mm, the scanning angle of the AOD 20 (the range of deflection angles that can be modulated) is 2 mrad, and the pixel size is 200 um × 200 um. In this case, the scannable range is 200 mm × 2 mrad = 400 um.

[0034] Here, since θ=0, Δx_max-Δx_min and Δy_max-Δy_min are, respectively, Δx_max-Δx_min=400um×cos(θ) / 200um=2 and Δy_max-Δy_min=400um×sin(θ) / 200um=0. In addition, Δy / Δx=tan(θ).

[0035] The scanning trajectory of the laser light by the galvano scanner 30 is the one when Δx is minimized (that is, Δx_min=0), and the pixel size is 200 um×200 um. In this case, Δx can be in the range of 0≦Δx≦2.

[0036] The first row in the main scan scans the row x=1, as in Figure 4(b). The (1,3) pixel is not a marking pixel (non-marking pixel), and the (2,3) pixel is an unmarked pixel. Therefore, when the laser light scanning trajectory is (x0,y0)=(1,3), the deflection angle of the AOD20 is controlled to make Δx=1, and the laser light, which was previously turned off, is turned on and irradiated at the position of the (2,3) pixel (unirradiated area).

[0037] Next, at the time when (x0, y0) = (1, 4), since pixel (1, 4) is a marking pixel, the deflection angle of the AOD 20 is controlled to set Δx = 0, and the (1, 4) pixel is irradiated with laser. Similarly, at (x0, y0) = (1, 5), the deflection angle of the AOD 20 is controlled to set Δx = 1, and the laser light that was previously turned off is turned on, and the (2, 5) pixel (unirradiated area) is irradiated with laser.

[0038] Up to this point, one main scan is completed, and marking is completed for two rows of x = 1, 2. Next, for example, select row x0 = 3 as the second main scan row, and set Δx to Δx = 1, 1, 0, 0, 1 for each of the galvano scanner scanning trajectory positions of (x0, y0) = (3, 5), (3, 4), (3, 3), (3, 2), and (3, 1), respectively.

[0039] By doing this, marking of the marking image in Figure 4(a) previously required four main scans, but can now be completed with two main scans. This reduction in the number of main scans (higher marking speed) is possible because a high-speed deflection scanning means such as the AOD20 can modulate the laser irradiation position for each pixel, making marking possible during times when the laser is turned off and marking is not possible with conventional general raster scanning.

[0040] In other words, by combining the galvanometer scanner 30 with the AOD 20, marking can be performed by instantaneous deflection scanning with the AOD 20 even at a timing when marking could not be performed by conventional general raster scanning using only the galvanometer scanner 30. This embodiment is particularly effective when it is desired to draw a relatively sparse image pattern such as a character (large room for utilizing laser output) in a short time by high-speed marking using raster scanning.

[0041] In Fig. 4(c), x0=3 in the second main scan, but it is also possible to use a scan with x0=2 as in Fig. 4(d). That is, Δx is set to Δx=2, 2, 1, 1, 2 for each of the galvano scanner 30 scanning trajectory positions (x0, y0)=(2, 5), (2, 4), (2, 3), (2, 2), (2, 1), respectively. The same effect can be obtained by scanning as in Fig. 4(d).

[0042] As shown in Fig. 4(d), the deflection angle of the laser light by the AOD 20, which is the first deflector, can be made different between the pth and p+qth raster scans at a given coordinate in the raster scan direction (p and q are any integers). That is, for example, in Fig. 4(d), when (x0, y0) = (1, 5), Δx = 1, whereas when (x0, y0) = (2, 5), Δx = 2.

[0043] As described above, there are various marking methods that can achieve the same effect (higher marking speed). However, depending on the conditions of the fθ lens 40, etc., if there is a constraint of Δx≦1, marking as shown in FIG. 4(d) is not possible, so the marking method shown in FIG. 4(c) is preferable.

[0044] ● Marking of 5 x 6 pixel images Next, an efficient marking method will be described for marking a 5x6 pixel image as shown in Fig. 5(a). Fig. 5(b) shows an example of marking when the deflection direction of the AOD20 is set to the +x direction, and Fig. 5(c) shows an example of marking when the deflection direction of the AOD20 is set to θ=-45° (diagonally upwards to the right in the figure). As with the definition of Δx, the amount of deviation of the y coordinate of the laser light due to the deflection angle control of the AOD20 is defined as Δy (unit: pixel) as a relative value from y0.

[0045] If the fθ lens focal length is 300 mm, the AOD 20 scanning angle of view is 2 mrad, and the pixel size is 200 um × 200 um, the scannable range of the AOD 20 is 600 um. Therefore, in Figure 5(b), 0≦Δx≦3, and in Figure 5(c), 0≦Δx, Δy≦2.1 (where Δy=-Δx).

[0046] In Fig. 5(b), a marking example will be described in which the deflection direction of the AOD 20 is the +x direction. In this case, the horizontal line in row y=1, 4 of the marking pattern is in the same direction as the deflection direction of the AOD 20, so as can be seen from Fig. 5(b), the right column cannot be marked first. For this reason, five main scans are required to complete the marking, and the effect of high-speed marking cannot be obtained.

[0047] In Fig. 5(c), a marking example will be described in which θ = -45° (diagonally upward right direction in the figure). In this case, as shown in Fig. 5(c), in the second row (x0 = 2) of the main scan, by setting (Δx, Δy) = (2, -2), (1, -1), (0, 0), (2, -2), (1, -1), (0, 0) for each of the scanning locus positions of the galvano scanner 30, (x0, y0) = (2, 6), (2, 5), (2, 4), (2, 3), (2, 2), (2, 1), respectively, it is possible to mark three rows, x = 2, 3, 4, in one main scan.

[0048] As a result, the 5 x 6 pixel marking pattern in Fig. 5(a) can be marked with three main scans. As can be seen from this example, it is easier to achieve high-speed marking by shifting the direction of the series of marking pixels that are continuous in one direction within the marking pattern and the deflection direction of the AOD 20. One example of a procedure for determining θ is to calculate the number of main scans required to complete marking for each of several different θ (for example, θ = 0°, -45°, 45°), and determine the angle that minimizes the number of main scans.

[0049] As suggested by the examples so far, when the sub-scanning direction is from -x to +x, efficient marking is possible by selecting a row that can mark the pixel with the smallest x coordinate (this x coordinate is x1) among unmarked pixels as the main scanning row of the galvano scanner 30. In other words, it is better to select x0 so that x0+Δx_min≦x1, with Δx_min being the minimum possible value for Δx. Since marking the row as far away as possible (closest to Δx_max) first leads to a reduction in marking time, x0+Δx_min=x1 may be used.

[0050] ● Marking using two AODs Although the above describes a marking method using only one AOD, the present embodiment is also applicable to a marking method using multiple AODs.

[0051] That is, as shown in Figures 6(a) and (b), it may be possible to further increase the marking speed by using two AODs, AOD 20 and AOD 23, to enable scanning in two directions. Figure 6(a) shows a plan view of a laser marking device 110 using two AODs, and Figure 6(b) shows a side view.

[0052] The polarization of the first-order diffracted light of AOD20 as the first deflector is aligned with the polarization axis of AOD23 as the third deflector by a half-wave plate, and the first-order diffracted light is diffracted by AOD23 in a direction perpendicular to the diffraction direction of AOD20 (+y direction in FIG. 6(b)). The first-order light (diffracted light) of AOD23 enters galvanometer scanner 30 and is focused on marking object 50 by fθ lens 40. In this configuration, by using two AODs, AOD20 and AOD23, it becomes possible to two-dimensionally control the laser irradiation position on marking object 50.

[0053] ● Marking of 13 x 8 pixel images An example of marking a 13×8 pixel image pattern is shown in Figure 7(a). Figure 7(b) shows an example of marking using only one AOD 20. Using one AOD 20 allows for more laser power to be used for the marking process compared to using two AODs.

[0054] As shown in Fig. 7(b), the deflection angle of the laser light by the AOD 20, which is the first deflector, can be made different between the pth and p+qth raster scans at a given coordinate in the raster scan direction (p and q are any integers). That is, for example, in Fig. 7(b), when (x0, y0) = (1, 5), Δx = 2, whereas when (x0, y0) = (11, 5), Δx = 1.

[0055] The marking flow in this case is shown in Figure 8. The fθ lens focal length is 300 mm, the AOD20 scanning angle of view is 2 mrad, and the pixel size is 100 um x 100 um.

[0056] The scanning trajectory of the laser light by the galvano scanner 30 is determined so that Δx_min = 0. In other words, the scanning trajectory of the galvano scanner 30 is determined based on the state in which the AOD 20 is deflected to the limit on the -x side.

[0057] If θ=45°, then 0≦Δx, Δy≦4.2 (where Δx=Δy). For example, as shown in Fig. 7(b), marking is completed in eight main scans in the marking method of Fig. 8.

[0058] 9, an example of marking the 13×8 pixel pattern shown in FIG. 7(a) will be described using two AODs 20 and 23. The solid line indicates the scanning trajectory of the galvano scanner 30, and the dotted arrows indicate the deflection by the AODs 20 and 23.

[0059] To avoid cluttering the diagram, the cross marks at the laser irradiation positions are omitted. Also, the start and end points of the dotted arrows are sometimes drawn shifted from the pixel center for convenience so that they do not overlap.

[0060] The deflection direction of AOD20 is the +x direction, and the deflection direction of AOD23 is the +y direction. The fθ lens focal length, AOD scanning angle of view, and pixel size are 300 mm, 2 mrad, and 100 um x 100 um, respectively, as in the example of Figure 7. In this case, Δx and Δy can each be selected from a width of 6 pixels, since the scannable range is 600 um and the pixel size is 100 um.

[0061] If the minimum value of Δy is Δy_min and the scanning trajectory of the galvano scanner 30 is determined so that Δx_min = 0, Δy_min = -3, the values ​​0≦Δx≦6, -3≦Δy≦3 can be obtained. The number of candidates for the destination to which the laser light is deflected by AOD control increases from 7 pixels in the case of one AOD to 49 pixels in the case of two AODs.

[0062] Since the two AODs 20, 23 provide two-way deflection freedom, the deflection direction can take different values ​​for each pixel, as can be seen in Fig. 9. With the drawing method of Fig. 9, the 13 x 8 pixel pattern (8 scans) of Fig. 7 can be marked with five main scans. Therefore, the drawing method of Fig. 9 (5 scans) can achieve 38% faster marking speed than the drawing method of Fig. 7 (8 scans). This allows for efficient drawing of complex marking patterns such as characters, resulting in a faster marking speed.

[0063] Table 1 below shows the settings of Δx and Δy for each (x0, y0) and the marking pixel coordinates in the first two main scans in FIG. [Table 1] Here, when two AODs 20 and 23 are used, the deflection direction of each AOD is selected to coincide with the main scanning direction and the sub-scanning direction, respectively. However, there is some freedom in selecting the deflection direction; for example, AOD 20 is in the θ=45° direction and AOD 23 is in the θ=-45° direction.

[0064] In addition, although the number of main scanning lines can be reduced by using two AODs 20 and 23, the diffraction efficiency of the AODs 20 and 23 is not 100% (for example, about 80%). Therefore, when using an AOD as a scanning means, the available laser power decreases if the scanning direction is two-directional (two-axis) (for example, 64% for two axes compared with 80% for one axis).

[0065] This is not a problem if there is sufficient laser power for marking, but there is a trade-off between laser power and marking speed. Therefore, in order to shorten the marking time, it is not desirable to reduce the available laser power.

[0066] ● Marking using one AOD Fig. 10 shows another embodiment different from that shown in Fig. 9. In this embodiment of Fig. 10, only one AOD 20 is used to mark the marking pattern (13 x 8 pixels) of Fig. 7(a). This makes it possible to avoid a decrease in laser power. For comparison with Fig. 7(b) and Fig. 9, the parameters related to the fθ lens 40 and AOD 20 and the pixel size are the same.

[0067] In other words, the fθ lens focal length is 300 mm, the scanning angle of the AOD20 is 2 mrad, and the pixel size is 100 um x 100 um. If Δx_min=-2 and θ=45°, then -2≦Δx, Δy≦2.2 (where Δx=Δy).

[0068] Unlike the example in Figure 7(b), in Figure 10 the main scanning range in the +y direction is two pixels longer than the length of the image pattern. By doing this, the time for one main scanning pass becomes two pixels longer, but the pixels that were originally at the end in the +y direction (for example, pixels (1,8) and (2,8)) can now be drawn from other columns.

[0069] As a result, the marking method shown in Fig. 10 can complete marking in six main scans. The marking flow is the same as that shown in Fig. 8. In the case of Fig. 7(b), eight main scans were required, so when the difference in main scan length is also taken into account, the time required for marking in the example of Fig. 10 can be reduced by about 6% compared to the example of Fig. 7(b) ((1 main scan time magnification) × (main scan count ratio) = (10 / 8) × (6 / 8) = 0.94).

[0070] In the example of Figure 10, two pixels are added to the +y side compared to the example of Figure 9. The number of added pixels and their positions are determined based on the relationship between the image pattern and the AOD scannable area. Therefore, depending on the relationship between the image pattern and the AOD scannable area, the number of added pixels may be more or less than the two pixels on the +y side in Figure 10, and the added direction may be either the +y side or the -y side.

[0071] In the embodiment of Fig. 10, a small image of 13 x 8 pixels was used for simplicity. Therefore, the marking time was reduced by at most 6%. However, for example, if the main scanning range of a 500 x 500 pixel image is increased by several to several tens of pixels (for example, 10 pixels) and the number of main scanning scans can be reduced to 8 / 10 times, the time reduction rate will be about 18%, and a greater effect will be obtained (510 / 500 x 8 / 10 = 0.82, 18% time reduction).

[0072] In the example of Figure 10, θ=45° is set to deflect the laser light to a pixel at (x0+k, y0+k) (k is an integer) with respect to the galvano scanning trajectory (x0, y0). If the pixel is not a square, a similar marking time reduction effect can be obtained by setting θ=arctan(Dy / Dx), where Dx is the pixel size in the x direction and Dy is the pixel size in the y direction.

[0073] That is, for example, when the pixel size is Dx×Dy=200um×100um, if θ=arctan(100 / 200)=0.464rad, the laser light can be deflected to a pixel of (x0+k,y0+k) (k is an integer) on the galvano scanning trajectory (x0,y0) (FIG. 11). Here, if θ=arctan(n×Dy / (m×Dx)) and the scannable area of ​​the AOD 20 is sufficiently large, any (x0+m,y0+n) pixel can be drawn on the galvano scanner 30 scanning trajectory (x0,y0).

[0074] Relationship between raster scanning line spacing and laser light irradiation density In marking, gaps (pixel gaps) caused by deviation in the irradiation position of the laser light are more noticeable in areas with a high image area ratio, such as solid areas. On the other hand, when multiple different deflection means are used in combination, such as a galvanometer scanner and an AOD, deviation in the irradiation position of the laser light occurs if the relative angle of the scanning direction deviates from the ideal relationship. In this case, the larger the deflection angle of the AOD, the greater the deviation in the irradiation position of the laser light.

[0075] This can be easily understood because there is no deviation in the irradiation position of the laser beam when there is no AOD (deflection angle θ = 0). Also, even if the irradiation surface of the laser beam shifts in the depth direction, the deviation in the irradiation position of the laser beam becomes large. For this reason, deviation in the irradiation position of the laser beam can easily become a problem when the target to be irradiated by the laser beam has a three-dimensional shape.

[0076] Therefore, it is conceivable that the image quality can be improved by narrowing the sub-scanning pitch in areas with a high image area ratio and drawing in areas with a small AOD deflection angle, while productivity can be improved by widening the sub-scanning pitch in areas with a low image area ratio.

[0077] The laser beam irradiation density (J / cm 2 An example of the calculation of d(m,n) is shown below. For the irradiation area (pixel) of coordinates (i,j), the function Z(i,j) is Z=1 if the pixel (i,j) is a drawing pixel, and Z=0 if not. For each irradiation area (pixel) (m,n), the irradiation density d(m,n) is

number

[0078] Fig. 12A shows a diagram in which d(m, n) is plotted for each irradiation region, and Fig. 12B shows the trajectory when plotted in the same manner as in Fig. 9. The circled numbers at the top of Fig. 12B indicate the number of scans, with 1-7 corresponding to the 1st to 7th scans in Table 2.

[0079] Here, the calculation area for calculating the irradiation density is set to a 3x3 pixel area. However, the calculation area for calculating the irradiation density may be larger or smaller than the 3x3 pixel area. In addition, the calculation area for calculating the irradiation density is not limited to a square, and may be, for example, a vertically or horizontally long rectangle.

[0080] The minimum x-coordinate at which the laser beam can be irradiated (deflected) in the i-th main scan is Ai, and the maximum irradiation density Di for the i-th main scan is "x = A i In areas with a high image area ratio, narrowing the sub-scanning pitch (scanning line interval) can improve image quality. For this reason, in at least two main scans (kth and lth) until laser irradiation is completed, D k >D l , and A k+1 -A k l+1 -A l (1) It is preferable for achieving both image quality and productivity that the above condition holds.

[0081] D for each scan​i The values ​​of and the sub-scanning pitch [line] are shown in Table 2. In this example, the relationship (1) above is satisfied in the combination of, for example, k=2, l=1. [Table 2]

[0082] The present invention allows the following embodiments by utilizing the above-mentioned relationship between the scanning line interval and the irradiation density. Aspect A A laser marking method using a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, comprising: The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; A laser marking method, characterized in that the interval between scanning lines in the raster scan is set based on the density of laser irradiation target regions per reference area on the object to be laser irradiated.

[0083] Aspect A' A laser marking method using a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, comprising: An irradiation density calculation step of calculating an irradiation density per area for each laser irradiation region before laser irradiation, The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; The minimum x coordinate that can be irradiated with laser light in the i-th main scan is Ai, and the maximum irradiation density Di for the i-th main scan is x=A i When the irradiation density is set to the maximum in the irradiation area of ​​at least two different main scans (kth and lth), Dk >D l , and A k+1 -A k l+1 -A l (1) a distance between scanning lines in the raster scan is set so as to satisfy the relationship:

[0084] Aspect B A laser irradiation device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; A laser irradiation device according to claim 1, wherein the interval between scanning lines in the raster scan is set based on the density of the laser irradiation target area per reference area on the object to be irradiated with the laser.

[0085] Mode B' A laser irradiation device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, an irradiation density calculation unit that calculates an irradiation density per area for each laser irradiation region before laser irradiation; The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; The minimum x coordinate that can be irradiated with laser light in the i-th main scan is Ai, and the maximum irradiation density Di for the i-th main scan is x=A i When the irradiation density is set to the maximum in the irradiation area of ​​at least two different main scans (kth and lth), D k >D l , and A k+1 -A k ​l+1 -A l (1) a distance between scanning lines in the raster scan is set so as to satisfy the relationship:

[0086] Aspect C A laser marking device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; A laser marking device characterized in that the interval between scanning lines in the raster scan is set based on the density of the laser irradiation target area per reference area on the laser irradiation object.

[0087] Aspect C' A laser marking device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, an irradiation density calculation unit that calculates an irradiation density per area for each laser irradiation region before laser irradiation; The laser light moving to the non-irradiated region of the laser irradiation object by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated region separated from the non-irradiated region; The minimum x coordinate that can be irradiated with laser light in the i-th main scan is Ai, and the maximum irradiation density Di for the i-th main scan is x=A i When the irradiation density is set to the maximum in the irradiation area of ​​at least two different main scans (kth and lth), D k >D l , and A k+1 -A k l+1 -A l (1) ​​The laser marking device according to claim 1, wherein the interval between the scanning lines in the raster scanning is set so as to satisfy the relationship:

[0088] ● Deflection angle θ 13, an example of deflecting laser light from pixel (1,1) to pixel (1+m,1+n) will be described for each of the cases where (m,n)=(1,1), (2,1), (1,2), and (2,3). By setting the relative angle (deflection angle θ) between the main scanning direction of the galvano scanner 30 and the AOD deflection direction in this way, the laser light can be deflected from the center of the pixel on the galvano scanner scanning trajectory (x0,y0) to the center of pixel (x0+m,y0+n), enabling highly accurate laser marking.

[0089] Here, as a method for adjusting the deflection angle θ, in addition to a method of rotating the AOD deflection direction about the z-axis in Fig. 1, a method of rotating the galvano scanner 30 about the z-axis, a method of rotating the scanning direction of the galvano scanner 30 without changing the optical system, etc. are also possible. Since the light incident on the AOD 20 needs to have a specific polarization direction with respect to the AOD 20, when the AOD 20 is rotated, the polarization of the incident light also needs to be rotated accordingly using a 1 / 2 wavelength plate or the like.

[0090] For example, when θ=arctan(Dy / (3Dx)) is used to deflect the laser light position from pixel (x0, y0) to the pixel center of another pixel, the laser light can be deflected only to a pixel represented by (x0+3k, y0+k), where k is an integer. However, this restriction can be relaxed by allowing the positional deviation of the marking position. That is, as shown in FIG. 14, by allowing the irradiation position deviation of Dy / 3 in the y direction (Dy is the pixel size in the y direction), the laser light of pixel (x0, y0) can be deflected to pixels represented by (x0+3k-2, y0+k-1), (x0+3k-1, y0+k) (k is an integer).

[0091] ● Tolerance for marking position deviation By allowing the marking position deviation as shown in Fig. 14, the marking speed can be increased. This increase in marking speed will be explained using the specific image pattern in Fig. 15(a). Fig. 15(a) is a marking example of a 4 x 9 pixel image pattern.

[0092] Here, θ=arctan(-Dy / (3Dx)). Figure 15(b) shows the scanning trajectory (solid arrow) of the laser light by the galvanometer scanner 30 during marking, and the deflection (dashed arrow) by the AOD 20. Table 3 below shows the AOD deflection control values ​​Δx and Δy for each (x0, y0) and the marking pixel coordinates x and y at that time. [Table 3]

[0093] When the marking pixel coordinate is a fraction, for example y=8 / 3, it represents a marking pixel position that is shifted from the pixel center by Dy / 3 toward the -y side from the pixel center of y=3 (Dy: pixel size in the y direction). By marking as shown in Fig. 15(b), it is possible to complete the marking in one main scan. However, Fig. 15(b) takes up an extra pixel in the main scan area on the +y side, just like Fig. 10.

[0094] So far, we have explained the case where the laser irradiation pitch calculated from the galvano main scanning speed and repetition frequency is equal to the pixel size, in other words, the case where the laser can be irradiated once while the galvano scanning trajectory passes over one pixel (and one pixel can be marked with one pulse), but we will also explain other cases.

[0095] Acceleration and deceleration of the main scanning speed The galvanometer scanner 30 needs to be accelerated until the main scanning speed becomes sufficiently high. For this reason, assuming the length required for acceleration (deceleration) is A, the main scanning length is L, and the marking image length in the main scanning direction is Y, when L - 2A < Y, the galvanometer scanner 30 is not sufficiently accelerated at the ends of the image area in the main scanning direction. Therefore, there may be cases where the laser beam can be irradiated two or more times while the galvanometer scanning trajectory passes through one pixel with insufficient acceleration.

[0096] For example, when L, A, and Y are in the relationship shown in FIG. 16 (image size is 13×8 pixels), the galvanometer scanner 30 is not sufficiently accelerated and operates at a low speed within the range of A at both the upper and lower ends. For this reason, there may be cases where the laser can be irradiated two or more times while the galvanometer scanning trajectory passes through the pixels at y = 1 (non-irradiated area) and y = 8 (irradiated area).

[0097] For multiple laser emissions at y = 1 and 8, different deflection controls (Δx, Δy) are given by the AOD 20 respectively. As a result, there may be a possibility of marking, for example, two pixels while passing through one pixel. This may shorten the marking time.

[0098] FIG. 16 shows an example of marking two pixels while passing through one pixel. That is, with the deflection angle θ = 0, at the pixel (x0, y0) = (1, 1) (non-irradiated area), two pixels (5, 1) and (6, 1) (non-irradiated areas) are marked. Similarly, at the pixel (x0, y0) = (1, 8) (irradiated area), two pixels, the pixel (1, 8) (irradiated area) and the pixel (2, 8) (non-irradiated area), are marked. Since the irradiation timings of each two pixels are different, the irradiation positions are shifted in the main scanning direction.

[0099] ● Marking using two AODs When two AODs 20 are used to enable two-dimensional deflection, such a shift in the main scanning direction can be eliminated. Here, the case of two irradiations has been described for simplicity, but the number of irradiations may be more than two. Also, the number of (x0, y0) where multiple irradiations are possible changes depending on the relationship with the acceleration / deceleration length and the pixel size.

[0100] Alternatively, for example, it is possible to set the laser irradiation pitch calculated from the galvanometer main scanning speed and repetition frequency to half the pixel size, and mark two pixels while passing one pixel, as shown in Figure 16. In Figure 17, θ=arctan(-Dy / 2Dx).

[0101] Although the laser irradiation pitch is half the pixel size as an example, the laser irradiation pitch may be smaller than half the pixel size. In that case, in principle, it is possible to mark two or more pixels while passing one pixel.

[0102] ●AOD sound beam As shown in Fig. 18, in the AOD 20, a sound wave is induced in the crystal by a transducer (oscillator) installed at one end of the AOD crystal as an actuator, and the laser light is diffracted by the refractive index distribution generated in the AOD crystal by the sound wave. Here, the diameter of the sound beam in the sound wave propagation direction is dx, and the diameter of the sound beam in the direction perpendicular to that is dy.

[0103] If the sound wave signal does not propagate through the entire laser beam, the laser beam will not diffract sufficiently. For this reason, the response speed of the AOD20 is approximately dx / V, where V is the speed of sound in the crystal. The smaller the beam diameter, the faster the control (high-speed deflection) becomes.

[0104] However, when using a high-power laser, reducing the beam diameter results in excessive light intensity, which can affect the light resistance of the optical devices. By making dy > dx, the light intensity can be reduced while maintaining high-speed deflection response, achieving both high-speed deflection response and light resistance of the optical devices.

[0105] Laser irradiation control unit and laser scanning control unit 19 is a block diagram of the laser irradiation control unit and the laser scanning control unit. Scanning unit 1 corresponds to a first deflector or a first scanning means, for example, an AOD 20, and scanning unit 2 corresponds to a second deflector or a second scanning means, for example, a galvano scanner 30.

[0106] How to control AOD The control method of the AOD 20 will be described for the marking example (five laser flashes) in Fig. 20(a). A timing chart of the AOD control is shown in Fig. 19(b). The aod_data signal is the frequency value (here, 4 bits) of the RF signal applied to the AOD element, and the frequency value is reflected in the AOD element by the latch signal.

[0107] Next, the laser light is turned on at the timing of the laser_pulse signal. The laser light is deflected in the x direction by the AOD element at an angle according to the frequency value set when the laser light is turned on.

[0108] The correspondence between the aod_data value and the deflection displacement Δx is as shown in the following Table 4. In order to adjust the timing of laser illumination and the timing of deflection by the AOD 20, it is desirable to be able to adjust the time between the laser_pulse signal and the latch signal. [Table 4]

[0109] The deflection angle control of the AOD20 is subject to the response time constraints imposed by the response characteristics of the AOD element (relationship between sound speed and beam diameter, etc.) and the electrical characteristics of the control unit. If the pulse lighting interval of the laser (the inverse of the repetition frequency) is T [s] and the time required to control the deflection angle of the AOD20 is τ [s], then if T ≥ τ, the deflection angle can be controlled independently for each pulse of the laser, providing a high degree of freedom and a large effect in speeding up marking.

[0110] When T<τ, the time required for deflection angle control is longer than the pulse lighting interval. This makes it necessary to discard pulses during deflection angle control (not lighting a pulse at a timing when it is possible to light a pulse). In this case, the effect of speeding up marking can be obtained by controlling the deflection angle to change as few times as possible.

[0111] ●Molding equipment The laser irradiation device according to the embodiment of the present invention can be applied to a three-dimensional object molding device. Fig. 21 shows a powder bed fusion bonding device 400, which is an example of the three-dimensional object molding device.

[0112] The powder bed fusion bonding apparatus 400 irradiates a powder bed in which multiple powder layers are formed sequentially with a laser beam to fuse and bond predetermined laser beam irradiated areas of the powder bed to form a three-dimensional object. Specifically, powder material is first spread evenly to form a layer. Next, a laser beam is irradiated at a desired position on the layer to selectively sinter or melt particles contained in the powder material to bond the particles.

[0113] This forms one layer by dividing the three-dimensional object into multiple layers in the thickness direction. The powder material is then spread on top of the layer of the object thus formed, and the next layer of the object is formed by irradiating it with laser light.

[0114] By repeating this procedure to build up layers of the object, a three-dimensional object of the desired shape is manufactured. The powder material includes a resin material or a metal material, etc., and two or more types may be mixed as appropriate, and additives may also be added.

[0115] The powder bed fusion bonding apparatus 400 includes a modeling stage 310, a layer formation unit 320, a pre-heating unit 330, a temperature measuring device 335, and a laser irradiation device 200. The modeling stage 310 is a stage on which a three-dimensional object is modeled. The stage support unit 350 supports the modeling stage 310 so that its vertical position can be variably changed.

[0116] The modeling stage 310 is configured to be precisely movable in the vertical direction by a stage support unit 350. Various configurations can be adopted for the stage support unit 350, but for example, it can be configured with a holding member that holds the modeling stage 310, a guide member that guides the holding member in the vertical direction, and a ball screw that engages with a screw hole provided in the guide member.

[0117] The layer forming unit 320 forms a layer. The layer forming unit 320 includes a powder supplying unit 321 that supplies powder and a recoater 322a that flattens the powder on the modeling stage 310.

[0118] The layer forming unit 320 includes, for example, an opening whose edge is on the same horizontal plane as the edge of the opening through which the modeling stage 310 rises and falls, and a powder material storage unit extending vertically downward from the opening. The powder supplying unit 321 includes a supply piston that is provided at the bottom of the powder material storage unit and rises and falls within the opening. The powder supplying unit 321 may also include a powder material storage unit provided vertically above the modeling stage 310 and a nozzle, and may be configured to eject powder material on the same horizontal plane as the modeling stage.

[0119] The preheating unit 330 preheats the layer formed in the layer forming unit 320. The preheating unit 330 may be any unit that can heat at least an area of ​​the surface of the layer where a model layer is to be formed, and maintain that temperature.

[0120] For example, the preheating unit 330 may be configured to include a first heater 331a capable of heating the surface of the layer formed on the modeling stage 310, or may further include a second heater 332 that heats the powder material before it is supplied onto the modeling stage. The preheating unit 330 may be configured to selectively heat an area where a modeling layer is to be formed, or may be configured to heat the entire inside of the device and adjust the surface of the formed layer to a predetermined temperature.

[0121] The first heater 331 may be heater 331a that heats the layer from the top, heater 331b that heats the layer from the side, heater 331c that heats the layer from the bottom, or any combination of these. However, the surface temperature of the layer is likely to increase in the vicinity of the first heaters 331a, 331b, and 331c, and the surface temperature of the layer is less likely to increase the farther away from the first heaters 331a, 331b, and 331c.

[0122] Therefore, from the viewpoint of preventing temperature unevenness on the surface of the layer and preventing deformation of the model layer due to temperature unevenness on the surface of the layer, it is preferable that the first heater 331 includes a plurality of heaters arranged separately from each other. In this case, it is preferable that the plurality of first heaters 331a, the plurality of first heaters 331b, and the plurality of first heaters 331c are arranged at equal intervals from each other.

[0123] The temperature measuring device 335 measures the temperature of the layer. Any device capable of measuring the surface temperature of the area where the model layer is to be formed in a non-contact manner may be used, such as an infrared sensor or an optical pyrometer.

[0124] The laser irradiation device 200 irradiates the powder bed with a laser beam. A model layer is formed by the irradiation of the laser beam. The laser irradiation device 200 includes a laser oscillator 10, an AOD 20, and a galvano scanner 30.

[0125] The laser irradiation device 200 may include a laser window 343 that transmits laser light. The laser window 343 may be made of any material that transmits laser light.

[0126] In the three-dimensional modeling apparatus 500, if there is unevenness in the pre-heating temperature applied by the pre-heating unit 330, there will also be unevenness in the rate of change in the volume (specific volume) of the powder irradiated with the laser light, resulting in a decrease in the accuracy of the three-dimensional model. Therefore, the temperature is measured by the temperature measuring device 335, and the energy of the laser light irradiated by the laser irradiation device 200 is adjusted according to the temperature result.

[0127] Specifically, when the preheating temperature is low, the energy imparted to the particles, which are the irradiated portions, from the laser light is increased, and when the preheating temperature is high, the energy imparted to the particles, which are the irradiated portions, from the laser light is decreased.

[0128] When the scanning means scans two or more irradiation regions and non-irradiation regions sandwiched between the irradiation regions, the laser irradiation device 200 controls the irradiation means and the scanning means so that the scanning speed is constant within the irradiation regions and the scanning speed is changed within the non-irradiation regions. In other words, in order to increase or decrease the energy by laser irradiation, the laser irradiation device 200 controls the energy by laser irradiation that the particle receives per unit time by changing the scanning speed of the laser scan.

[0129] In the laser irradiation device 200 of Fig. 21, the scanning speed can be precisely controlled for each irradiation region, and therefore the energy of the laser light given to the powder particles for sintering or melting can be precisely controlled. As a result, the rate of change in the volume (specific volume) of the resin caused by unevenness in the preliminary temperature can be made uniform, and the resulting decrease in the accuracy of the three-dimensional object can be prevented. Furthermore, in the raster scanning of the laser light, the laser output can be effectively utilized and productivity can be improved.

[0130] Although the present invention has been specifically described above based on the embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways within the scope of the technical ideas described in the claims. For example, in the above embodiments, the first-order diffracted light of the AOD 20 is used, but the same effect can be obtained by using the first-order light or higher-order light of the second order or higher. It is also possible to use a combination of light of multiple orders, such as using both the zeroth-order light and the first-order light.

[0131] <Additional Notes> Preferred aspects of the present invention will be described below. <First aspect> The first aspect is a laser irradiation method that uses a first deflector and a second deflector for deflectively scanning a laser beam, and irradiates a laser beam deflected by the first deflector onto an object to be irradiated with the laser beam by raster scanning using the second deflector, characterized in that the laser beam that moves to a non-irradiated area of ​​the object to be irradiated with the laser beam by the raster scanning is deflected by the first deflector so as to be irradiated onto an unirradiated area spaced from the non-irradiated area. <Second aspect> A second aspect is the laser irradiation method according to the first aspect, characterized in that the unirradiated region is a region spaced apart from the raster scan. <Third aspect> A third aspect is the laser irradiation method according to the first or second aspect, characterized in that the first deflector has an acousto-optic deflector or an electro-optic deflector. <Fourth aspect> A fourth aspect is the laser irradiation method according to any one of the first to third aspects, characterized in that the first deflector deflects the laser light in a direction different from a scanning direction of the raster scan. <Fifth aspect> A fifth aspect is a laser irradiation method according to any one of the first to fourth aspects, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector. <Sixth aspect> A sixth aspect is a laser irradiation method according to any one of the first to fifth aspects, characterized in that the spacing between the scanning lines by the raster scanning is set based on the density of the laser irradiation target area per reference area on the laser irradiation object. <Seventh aspect> A seventh aspect is a laser marking method that uses a first deflector and a second deflector for deflecting and scanning a laser beam, and irradiates the laser beam deflected by the first deflector onto an object to be laser-irradiated by raster scanning by the second deflector, characterized in that when the raster scanning by the second deflector accelerates or decelerates, the laser beam that moves to an irradiated area or a non-irradiated area of ​​the object to be laser-irradiated by the raster scanning is deflected by the first deflector so as to be irradiated onto an unirradiated area spaced from the irradiated area or the non-irradiated area. <Eighth aspect> An eighth aspect is the laser marking method of the seventh aspect, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector, thereby reducing the positional deviation in the raster scanning direction of the laser irradiation position relative to the unirradiated area. <Ninth aspect> A ninth aspect is a laser irradiation device including a first deflector and a second deflector for deflecting and scanning a laser beam, and irradiating a laser beam deflected by the first deflector onto a laser irradiation object by raster scanning by the second deflector, This laser irradiation device is characterized in that the laser light moving to the non-irradiated area of ​​the laser irradiation object by the raster scanning is deflected by the first deflector so as to irradiate an unirradiated area separated from the non-irradiated area. <Tenth aspect> A tenth aspect is the laser irradiation device according to the ninth aspect, characterized in that the non-irradiated region is a region spaced apart from the raster scan. <Eleventh aspect> An eleventh aspect is the laser irradiation device according to the ninth or tenth aspect, characterized in that the first deflector has an acousto-optic deflector or an electro-optic deflector. <Twelfth aspect> A twelfth aspect is the laser irradiation device according to any one of the ninth to eleventh aspects, characterized in that the first deflector deflects the laser light in a direction different from a scanning direction of the raster scan. <Thirteenth aspect> A thirteenth aspect is a laser irradiation device according to any one of the ninth to twelfth aspects, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector. <14th aspect> A fourteenth aspect is a laser marking device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, and irradiating an object to be laser-irradiated with the laser beam deflected by the first deflector by raster scanning by the second deflector, characterized in that when the raster scanning by the second deflector accelerates or decelerates, the laser beam moving to an irradiated area or a non-irradiated area of ​​the object to be laser-irradiated by the raster scanning is deflected by the first deflector so as to be irradiated to an unirradiated area spaced from the irradiated area or the non-irradiated area. <Fifteenth aspect> A fifteenth aspect is the laser marking device of the fourteenth aspect, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector, thereby reducing the positional deviation in the raster scanning direction of the laser irradiation position relative to the unirradiated area. <16th aspect> A sixteenth aspect is the laser irradiation device according to any one of the ninth to fifteenth aspects, characterized in that the deflection angle of the laser light by the first deflector is made different between the pth and the p+qth raster scans at a predetermined coordinate in the raster scan direction (p and q are any integers). <17th aspect> The 17th aspect is a molding apparatus characterized in that it is configured to mold a three-dimensional object by repeatedly irradiating a laser onto an irradiation area of ​​a powder bed in which powder layers are formed sequentially in multiple layers using a laser irradiation device of any one of the 9th to 16th aspects. <18th aspect> An eighteenth aspect is a laser marking device which includes a laser light source which outputs laser light, a first scanning means which scans the laser light, and a second scanning means which scans the laser light which has passed through the first scanning means, and which performs marking on an object to be marked, wherein the second scanning means performs approximately raster scanning, the marking pattern includes a plurality of main scan lines, the plurality of main scan lines include at least a first main scan line and a second main scan line, the first main scan line includes a first irradiation position, and the second main scan line includes a second irradiation position, and the deflection angle of the first scanning means is controlled to irradiate the first irradiation position with a laser, and then irradiate the second irradiation position with a laser. <19th aspect> A 19th aspect is the laser marking device of the 18th aspect, characterized in that during marking operation, when the deflection angle of the first scanning means is a reference value, the main scanning axis of the second scanning means always coincides with one of the columns of the marking image, and the first scanning means deflects laser light to a pixel to be drawn on a drawing column other than the main scanning axis. <20th aspect> A 20th aspect is a laser marking device according to the 18th or 19th aspect, characterized in that the main scanning direction of the second scanning means is y and the sub-scanning direction is x, the sub-scanning direction of the second scanning means is a direction from the negative direction of x to the positive direction, and in at least one main scan, a pixel with the smallest x (this x coordinate is x1) among the marking pixels that can be marked in at least one y (row) is marked, and a pixel with an x ​​coordinate different from x1 is marked in at least one different y in the same main scan. <21st aspect> A 21st aspect is the laser marking device of the 20th aspect, characterized in that, in at least one main scan, the minimum x coordinate capable of marking, determined from the relationship between the deflection range of the first scanning means and the deflection angle of the second scanning means, coincides with the x coordinate of a marking pixel that has not been drawn at the time of that main scan. <22nd aspect> A twenty-second aspect is the laser marking device according to any one of the eighteenth to twenty-first aspects, characterized in that the first scanning means is an acousto-optical element or an electro-optical element. <23rd aspect> A twenty-third aspect is the laser marking device according to any one of the eighteenth to twenty-second aspects, characterized in that the first scanning means is capable of scanning in only one direction. This improves the efficiency of laser light utilization, and enables the laser power available for marking processing to be increased. <24th aspect> A 24th aspect is the laser marking device of the 23rd aspect, characterized in that the second scanning means is capable of scanning in two directions, and when the angle between the scanning direction of the first scanning means and the sub-scanning direction of the second scanning means is θ, the sub-scanning direction size of the marking image area is larger than the value obtained by multiplying the scannable length of the second scanning means by cos(θ). <25th aspect> A 25th aspect is the laser marking device of the 23rd or 24th aspect, characterized in that θ is given by θ = ±arctan((nDy) / (mDx)) when the dot spacing in the main scanning direction is Dy [m], the dot spacing in the sub-scanning direction is Dx [m], and n and m are natural numbers. By giving θ by the above relational expression, the coordinates of the deflected point by the AOD can be made to coincide with the position of the marking pixel. <26th aspect> A 26th aspect is the laser marking device according to the 23rd or 25th aspect, characterized in that the θ is set based on an image pattern, and the deflection direction of the first scanning means is different from the direction of the longest line segment in the image pattern. Since there are deflection directions that are suitable for different drawing patterns, the effect of increasing marking speed can be increased by determining the direction according to the image pattern. For example, for a pattern with many horizontal lines, the speed can be increased by shifting the deflection direction from 0 degrees (horizontal). <27th aspect> In the 27th aspect, when the deflection angle of the first scanning means is set as the first deflection angle, the value of the first deflection angle when drawing the nth pixel is a, and the value of the first deflection angle when drawing the (n + 1)th pixel is b, during the period from drawing the nth pixel to drawing the (n + 1)th pixel, if a < b, the first deflection angle satisfies the relationship of a ≤ the first deflection angle ≤ b, and if a > b, the first deflection angle satisfies the relationship of a ≥ the first deflection angle ≥ b. It is a laser marking device according to any one of the 18th aspect to the 26th aspect. (n represents the temporal order of the drawn pixels) Thereby, the deflection angle can be controlled with the shortest processing time. <The 28th aspect> The 28th aspect is a laser marking device according to any one of the 18th aspect to the 27th aspect, characterized in that the time required for changing the deflection angle of the first scanning means from drawing one pixel to drawing the next pixel is made equal to or less than the lighting period of the laser. For all pulses of the laser, the deflection angle modulation by the first scanning means can be set to independent values. If this relationship is not satisfied, drawing will be performed at the same deflection angle for two or more consecutive pulses, and at least one pulse will be discarded (not used for drawing) when changing the deflection angle. <The 29th aspect> The 29th aspect is a laser marking device according to any one of the 25th aspect to the 28th aspect, characterized in that θ has a predetermined value other than 0. According to this aspect, it is advantageous for writing horizontal lines. <The 30th aspect> The 30th aspect is a laser marking device according to any one of the 18th aspect to the 29th aspect, characterized in that when the second scanning means is accelerating or decelerating in the main scanning direction, laser light can be emitted more times than the number of pixels through which the laser light trajectory generated by the second scanning means passes, and for each laser emission, the second deflection angle is controlled to move the laser light to different marking target points. According to this aspect, by picking up the laser pulses that have been discarded conventionally in the non-uniform speed region with an AOD and effectively using them for marking, the marking can be speeded up. <The 31st aspect> A 31st aspect is a laser marking device of any one of the 18th to 30th aspects, characterized in that the first scanning means is an acousto-optical element, and the beam diameter of the laser light incident on the first scanning means in the deflection direction is smaller than the beam diameter in the direction perpendicular to the deflection direction. According to this embodiment, it is possible to achieve both the light resistance of each optical device and the high speed response of the AOD. [Explanation of symbols]

[0132] 10: Laser oscillator (laser light source) 20: Acousto-optic deflector (first deflector) 21: Beam dumper 30: Galvano scanner (second deflector) 40: fθ lens (condenser lens) 50: Marking object 100, 110: Laser marking device 200: Laser irradiation device 320: Layer forming section 321: Powder supply section 322a: Recoater 330: Preheating section 331a: First heater 331b, 331c: Heaters 332: Second heater 335: Temperature measuring device 343: Laser window 350: Stage support [Prior art documents] [Patent documents]

[0133] [Patent Document 1] Patent No. 4108294

Claims

1. A laser irradiation method using a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation target, the method comprising: A laser irradiation method, characterized in that the laser light moving to a non-irradiated area of ​​the laser irradiation object by the raster scanning is deflected by the first deflector so as to irradiate an unirradiated area separated from the non-irradiated area.

2. 2. The laser irradiation method according to claim 1, wherein the non-irradiated region is a region spaced from the raster scan.

3. 2. The laser irradiation method according to claim 1, wherein the first deflector comprises an acousto-optic deflector or an electro-optic deflector.

4. 2. The laser irradiation method according to claim 1, wherein the laser light is deflected by the first deflector in a direction different from a scanning direction of the raster scan.

5. 2. The laser irradiation method according to claim 1, wherein a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector.

6. 2. The laser irradiation method according to claim 1, wherein the intervals between the scanning lines in the raster scan are set based on the density of the laser irradiation target regions per reference area on the object to be irradiated with the laser.

7. A laser marking method using a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being irradiated onto an object to be laser-irradiated by raster scanning using the second deflector, A laser marking method characterized in that, when the raster scanning by the second deflector accelerates or decelerates, the laser light moving to the irradiated area or non-irradiated area of ​​the laser irradiation object by the raster scanning is deflected by the first deflector so as to irradiate an unirradiated area spaced from the irradiated area or non-irradiated area.

8. The laser marking method of claim 7, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector, thereby reducing positional deviation in the raster scanning direction of the laser irradiation position relative to the unirradiated area.

9. A laser irradiation device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, A laser irradiation device characterized in that the laser light moving to a non-irradiated area of ​​the laser irradiation object by the raster scanning is deflected by the first deflector so as to irradiate an unirradiated area separated from the non-irradiated area.

10. 10. The laser irradiation device according to claim 9, wherein the non-irradiated area is an area spaced from the raster scanning area.

11. 10. The laser irradiation apparatus of claim 9, wherein the first deflector comprises an acousto-optic deflector or an electro-optic deflector.

12. 10. The laser irradiation device according to claim 9, wherein the first deflector deflects the laser light in a direction different from a scanning direction of the raster scan.

13. 10. The laser irradiation device according to claim 9, wherein a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector.

14. A laser marking device comprising a first deflector and a second deflector for deflecting and scanning a laser beam, the laser beam deflected by the first deflector being raster-scanned by the second deflector to irradiate a laser irradiation object, A laser marking device characterized in that, when the raster scanning by the second deflector accelerates or decelerates, the laser light moving to the irradiated area or non-irradiated area of ​​the laser irradiation object by the raster scanning is deflected by the first deflector so as to irradiate an unirradiated area spaced from the irradiated area or non-irradiated area.

15. The laser marking device of claim 14, characterized in that a third deflector between the first deflector and the second deflector deflects the laser light deflected by the first deflector in a direction different from the deflection direction of the first deflector, thereby reducing positional deviation in the raster scanning direction of the laser irradiation position relative to the unirradiated area.

16. 10. The laser irradiation device of claim 9, wherein the deflection angle of the laser light by the first deflector is made different between the pth and the p+qth raster scans at a predetermined coordinate in the raster scanning direction. (p and q are any integers)

17. 10. A molding apparatus configured to mold a three-dimensional object by repeatedly irradiating a laser beam by the laser irradiation device of claim 9 onto an irradiation area of ​​a powder bed in which powder layers are successively formed in a plurality of layers.

Images