JP2024081837A - Laser irradiation device and laser irradiation method - Google Patents

Abstract

To reduce the total time of laser irradiation and to maintain the irradiation accuracy of laser irradiation.SOLUTION: A laser irradiation device includes: irradiation means which emits laser light; scan means which scans the laser light emitted by the irradiation means; and a control unit that controls the irradiation means and the scan means so as to scan at a constant speed in an irradiation region and change a scan speed in a non-irradiation region when the scan means scans the two or more irradiation regions and the non-irradiation region sandwiched by the irradiation regions.SELECTED DRAWING: Figure 6

Description

The present invention relates to a laser irradiation device and a laser irradiation method.

Processing techniques using lasers are known. One example is a laser device that prints product codes on products (see Patent Document 1).

The objective of the present invention is to shorten the total time of laser irradiation while at the same time maintaining the accuracy of laser irradiation.

The laser irradiation device of the present invention is a laser irradiation device equipped with an irradiation means for irradiating laser light and a scanning means for scanning the laser light irradiated by the irradiation means, and has a control unit that controls the irradiation means and the scanning means so that when the scanning means scans two or more irradiation areas and non-irradiation areas sandwiched between the irradiation areas, the irradiation areas are scanned at a constant speed and the scanning speed is changed in the non-irradiation areas.

The present invention makes it possible to reduce the total time of laser irradiation while maintaining the accuracy of laser irradiation.

1 is a top view showing a configuration example of a laser irradiation device according to an embodiment of the present invention; 1 is a side view showing a configuration example of a laser irradiation device according to an embodiment of the present invention; 3 is a view of the container as viewed from the direction of the arrow D in FIG. 2. 5A to 5C are diagrams illustrating the operation of a galvanometer mirror according to an embodiment of the present invention. FIG. 4 is a diagram showing an irradiation area of a laser beam according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the scanning speed (v) of a laser beam and time (t) according to an embodiment of the present invention. FIG. 13 is a diagram illustrating the application of acceleration and deceleration in illuminated and non-illuminated areas according to an embodiment of the present invention. FIG. 2 is a block diagram showing a hardware configuration of a control unit according to an embodiment of the present invention. 2 is a block diagram showing a functional configuration of a control unit according to an embodiment of the present invention; FIG. FIG. 4 is a diagram showing an acceleration/deceleration trajectory for suppressing excitation of resonance during acceleration/deceleration according to an embodiment of the present invention. 2A to 2C are diagrams showing a first configuration example of a laser light intensity profile and processing mark formation by a pulse laser according to an embodiment of the present invention. 5A to 5C are diagrams showing a second configuration example of a laser light intensity profile and processing mark formation by a pulse laser according to one embodiment of the present invention. 3A to 3C are diagrams showing a first configuration example of a laser light intensity profile and processing mark formation by a CW laser according to one embodiment of the present invention. 5A to 5C are diagrams showing a second configuration example of a laser light intensity profile and processing mark formation by a CW laser according to one embodiment of the present invention. 4 is a flow chart of generating a scan velocity profile according to an embodiment of the present invention. 11A and 11B are diagrams showing changes in properties of a base material of a container according to one embodiment of the present invention. 1 is a side view showing a configuration example of a three-dimensional object forming apparatus according to an embodiment of the present invention;

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are given the same reference numerals, and duplicated descriptions will be omitted.

[Embodiment]
<Configuration example of laser irradiation device 200>
First, a laser irradiation device 200 according to an embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a top view showing a configuration example of a laser irradiation device 200 according to an embodiment of the present invention. Fig. 2 is a side view showing a configuration example of a laser irradiation device according to an embodiment of the present invention. Fig. 3 is a view of a container viewed from the direction of arrow D in Fig. 2. The laser irradiation device 200 shown in Figs. 1 to 3 forms a pattern by irradiating an irradiation surface 200 of a container 1 with a laser beam 202 as an example of processing. Processing can be appropriately applied to examples other than pattern formation.

First, we will explain Figure 1. The laser irradiation device 200 has a pulse laser 21 and a beam expander 22 as irradiation means, and a galvanometer mirror 221, a polygon mirror 231, and an fθ lens 241 as scanning means. The laser irradiation device 200 is also connected to a transport detection unit 300 and a control unit 6. The transport detection unit 300 includes a transport detection light emitting element 301 and a transport detection light receiving element 302.

(Irradiation Means)
The irradiation means irradiates laser light 202. As the irradiation means, a pulsed laser 21 irradiates the laser by repeatedly blinking at short time intervals. As the irradiation means, a continuous wave laser (CW (Continuous Wave) laser) may be used instead of the pulsed laser 21. A continuous wave laser is a laser that continuously oscillates laser light. Regardless of the type of laser, the surface or inside of the base material constituting the container 1 can be irradiated with laser light 202 to thermally deform the base material. As a result, a pattern is formed in the container 1.

A laser beam 202 from a pulsed laser 21 is irradiated onto the surface of a base material constituting a container 1, such as a PET bottle, which is being transported in the direction of arrow A. In addition, by irradiating the laser beam 202, the state of the surface of the base material of the container 1 may be changed, or the inside of the base material may be changed.

The pulsed laser 21 is a light source that emits laser light. The pulsed laser 21 emits a roughly parallel pulsed laser beam in the positive direction of the Y axis. The pulsed laser 21 can also switch between emitting laser light of three different oscillation wavelengths: a fundamental wave with an oscillation wavelength of 1064 nanometers, a second harmonic with an oscillation wavelength of 532 nanometers, and a third harmonic with an oscillation wavelength of 355 nanometers.

For all oscillation wavelengths, the pulse width of the laser light is 15 picoseconds or less. The repetition frequency of the laser light can be appropriately selected within a range from single shot to 200 kHz. The beam diameter of the laser light is approximately 2.0 mm for the fundamental wave, approximately 1.4 mm for the second harmonic, and approximately 1.3 mm for the third harmonic.

The pulse laser 21 can be, for example, a fiber laser-based Talisker Ultra 355-4 manufactured by Coherent. However, it is not limited to this, and other pulse lasers can also be used.

The pulse laser 21 can also be switched between emission (on) and non-emission (off) based on the pattern data of the pattern to be formed on the container 1.

The laser irradiation device 200 may use a beam expander 22 as an irradiation means in addition to the pulsed laser 21 or CW laser. The beam expander 22 is disposed on the positive Y-axis side of the pulsed laser 21. The beam expander 22 is an optical system that emits a substantially parallel laser beam in the positive Y-axis direction, the beam diameter of the laser light emitted by the pulsed laser 21 being expanded by a predetermined expansion factor.

(Scanning Means)
The scanning means scans the laser light 202 irradiated by the irradiation means. The scanning means includes a galvanometer mirror 221, a polygon mirror 231, and an fθ lens 241. As another example, the scanning means may include at least one of the galvanometer mirror 221 and the polygon mirror 231, and may further include an fθ lens 241 as necessary.

The galvanometer mirror 221 is disposed on the Y-axis positive side of the beam expander 22. The galvanometer mirror 221 deflects the laser light, the beam diameter of which has been expanded by the beam expander 22, toward the Z-axis positive side. The galvanometer mirror 221 also uses a motor as a drive source to swing in the direction of arrow B, thereby scanning the laser light from the beam expander 22 in the transport direction.

Polygon mirror 231 is disposed on the negative Y-axis side of galvanometer mirror 221. Polygon mirror 231 scans the laser light by rotating.

Now, referring to FIG. 2, the polygon mirror 231 will be described. The polygon mirror 231 scans the laser light in the direction of the arrow C. The polygon mirror 231 is a rotating polygonal mirror that can be rotated using a motor or the like as a drive source, and includes multiple reflective surfaces. The polygon mirror 231 rotates around an axis parallel to the X-axis (in the direction of the arrow B') to change the angle of the reflective surfaces, thereby scanning the laser light incident from the galvanometer mirror 221 in the direction of the arrow C. In FIG. 2, the polygon mirror 231 has six reflective surfaces, but the number of reflective surfaces is not limited as long as it is a polygonal mirror.

The fθ lens 241 irradiates the laser light 202 scanned by the polygon mirror 231 onto the base material constituting the container 1. The fθ lens 241 is a lens designed and manufactured so that the scanning speed of the laser light 202 that passes through the peripheral and central parts of the fθ lens 241 is approximately constant. The fθ lens 241 is also designed and manufactured so as to focus the laser light on the base material that constitutes the container 1 and is placed at a predetermined position. The fθ lens 241 may be composed of a single lens, or the function of the fθ lens 241 may be realized by combining multiple lenses, or the function of the fθ lens 241 may be realized by a configuration including optical elements other than lenses such as mirrors.

The laser irradiation device 200 places the container 1 on the positive Y-axis side of the fθ lens 241, and irradiates the laser light 202 onto the irradiated surface 400 of the container 1 that faces the fθ lens 241. The laser irradiation device 200 also places the container 1 on a transport unit such as a belt conveyor, and transports it in the direction of arrow A (transport direction) perpendicular to the Y-axis.

(Transportation detection unit)
The transport detection unit 300 detects the timing of forming a pattern on the container 1. The laser irradiation device 200 is provided with the transport detection unit 300 on the upstream side in the direction of the arrow A, which detects the container 1 being transported. The transport detection unit 300 includes a transport detection light emitting element 301 and a transport detection light receiving element 302. The transport detection unit 300 detects the timing when the container 1 blocks the light that the transport detection light emitting element 301 irradiates toward the transport detection light receiving element 302. The laser irradiation device 200 detects the timing when the container 1 being transported enters the irradiation position of the laser light 202 based on this light blocking timing and distance information between the irradiation position of the laser light 202 and the transport detection unit 300, and determines the start timing of pattern formation in the transport direction.

The laser irradiation device 200 can also sequentially irradiate the base material of each of the multiple containers 1 that are sequentially transported by a transport unit such as a belt conveyor with laser light. This forms a pattern on the irradiated surface 400 of the container 1.

(Control unit 6)
The control unit 6 controls the laser irradiation device 200. Specifically, the control unit 6 is responsible for various controls related to software.

Next, FIG. 2 will be described. The laser irradiation device 200 has a pulse laser 21 and a beam expander 22 as irradiation means, and a galvanometer mirror 221, a polygon mirror 231, and an fθ lens 241 as scanning means. The laser irradiation device 200 is connected to a transport detection unit 300 and a control unit 6. Furthermore, FIG. 2 has a synchronous detection unit 25, which includes a synchronous detection LD (Laser Diode) 251 and a synchronous detection PD (Photo Diode) 252. Descriptions of configurations in FIG. 2 that overlap with FIG. 1 will be omitted.

The polygon mirror 231 scans the laser light in the direction of the arrow C. The direction of the arrow A in FIG. 1 corresponds to the conveying direction, but the direction of the arrow C in FIG. 2 corresponds to the intersecting direction intersecting the conveying direction. The laser irradiation device 200 irradiates the laser 202 in the direction of the arrow C to form a pattern on the container 1. The polygon mirror 231 is a rotating polygonal mirror that can be rotated by a motor or the like as a drive source, and includes multiple reflective surfaces. The polygon mirror 231 rotates around an axis parallel to the X-axis (in the direction of the arrow B') to change the angle of the reflective surface, thereby scanning the laser light incident from the galvanometer mirror 221 in the direction of the arrow C. The polygon mirror 231 has six reflective surfaces, but the number of reflective surfaces is not limited if it is a polygonal mirror.

A synchronous detection unit 25 is provided near the polygon mirror 231. The synchronous detection unit 25 includes a synchronous detection LD (Laser Diode) 251 and a synchronous detection PD (Photo Diode) 252. The synchronous detection LD 251 emits laser light toward the polygon mirror 231, and the synchronous detection PD 252 receives the reflected light from the polygon mirror 231. The laser irradiation device 200 determines the start timing of pattern formation in the intersecting direction based on the light receiving signal of the synchronous detection PD 252.

The laser irradiation device 200 is triggered by the start timing of pattern formation in both the conveying direction and the cross direction, and irradiates the container 1 being conveyed with laser light 202 extending in the direction of arrow C while controlling the on/off of the pulse laser 21 based on the pattern data.

Next, we will explain Figure 3. We will omit the explanation of the configuration of Figure 3 that overlaps with Figures 1 and 2.

Figure 3 shows an example in which a pattern 401 is formed on the irradiated surface 400 of the container 1.

Lx indicates the length of the pattern 401, which is the irradiation target area irradiated with the laser light 202, in the horizontal direction C of the container 1. Furthermore, Lz indicates the length of the pattern 401, which is the irradiation target area, in the vertical direction (A direction) of the container 1.

<Productivity of Pattern Formation by Laser Irradiation Apparatus 200>
A pattern is formed by thermally deforming the substrate by irradiating the surface or interior of the substrate constituting the container 1 with laser light 202. The laser light may be either a pulsed laser 21 or a continuous wave laser (CW laser). However, since the pulsed laser 21 is a laser that repeatedly blinks at short time intervals, the productivity of pattern formation depends on the repetition frequency of the emission of the laser light. The productivity of a pulsed laser having such characteristics will be explained below.

If the container size is W [mm], the distance between multiple containers 1 in the transport direction is d [mm], and the productivity of pattern formation is X [pieces/min], the transport speed V [mm/s] of the container 1 is calculated using the following formula. Note that the distance between multiple containers 1 in the transport direction is equal to the distance between multiple substrates in the transport direction.

Also, assuming that the pixel density is a [dpi], the time T allowed per scan by the polygon mirror 231 to ensure productivity X is calculated using the following formula:

Furthermore, if the pattern formation area in the intersecting direction is Lz [mm], the time Δt [s] allowed per dot in the intersecting direction to ensure productivity X is calculated using the following formula:

Next, we will explain the fluence of laser light.

The fluence F of laser light can be expressed as follows:

where P [W] represents the average output (light intensity) of the pulsed laser, E [J] represents the pulse energy per pulse of the laser light, ν [Hz] represents the repetition frequency of the laser light emission by the pulsed laser, F [J/cm ² ] represents the fluence, and S [cm ² ] represents the area of the laser beam spot.

The fluence F corresponds to the value obtained by dividing the pulse energy by the area of the laser beam spot. The fluence at the substrate constituting the container 1 is the value obtained by dividing the pulse energy of the laser light emitted by the pulse laser 21 by the area of the laser beam spot on the substrate constituting the container 1.

When using laser light with a nanosecond-scale pulse width, the laser irradiation device 200 forms a pattern through thermal denaturation according to the absorption spectrum of the substrate. On the other hand, when using laser light with a picosecond-scale pulse width, the laser irradiation device 200 forms a pattern through thermal denaturation according to both the absorption spectrum and multiphoton absorption.

Multiphoton absorption is a nonlinear phenomenon in which, when irradiated with laser light, a state is created in which the material is excited by light with a wavelength corresponding to 1/2 or 1/3 of the oscillation wavelength of the laser light, and multiple photons are absorbed, causing the state of electrons and atoms to transition to a higher energy level. By using laser light with a pulse width on the picosecond scale, the substrate can be sublimated from a solid state without passing through a molten state, and processing marks can be formed on the substrate.

In this case, if a pulsed laser 21 is selected that is capable of forming a pattern of one dot per pulse, the fluence required to irradiate the substrate of the container 1 with laser light is the repetition frequency ν [Hz].

On the other hand, if the fluence of the pulsed laser 21 is small and N pulses are required to form a one-dot pattern, the pattern formation frequency is ν/N [Hz], and the time required to form one dot pattern is N/ν [s].

In this case, only values greater than N/ν [s] are allowed for Δt, and the container 1 cannot be transported at a speed faster than the speed allowed for pattern formation in one scan. In other words, the time allowed for pattern formation of one dot becomes the rate limiting factor for productivity.

In contrast, in this embodiment, the polygon mirror 231 scans the laser light in the intersecting direction at multiple positions in the transport direction of the container 1. The more multiple positions in the transport direction there are, the slower the apparent transport speed of the container 1 becomes, and the longer the pattern formation time can be.

<Example of laser irradiation device in action>

Figure 4 is a diagram showing the operation of a galvanometer mirror according to one embodiment of the present invention. Figure 4(a) shows an example of scanning in the positive direction of the X-axis, and Figure 4(b) shows an example of scanning in the negative direction of the X-axis. By oscillating the galvanometer mirror along arrow B, the laser light 202 by the polygon mirror 231 can be scanned in the direction of arrow A. In Figure 4(a), the laser light 202 is scanned in the positive direction of the X-axis, and in Figure 4(b), the laser light 202 is scanned in the negative direction of the X-axis. In other words, the polygon mirror 231 scans the laser light 202 in intersecting directions at two positions in the transport direction.

In this way, by scanning the laser light 202 in the A direction in the X-axis direction using the galvanometer mirror 221 and in the C direction in the Z-axis direction using the polygon mirror 231, it is possible to irradiate the laser light 202 at any position on the irradiated surface 400.

Note that while the A direction is the direction in which the galvanometer mirror 221 scans the laser light 202, the A direction is also the direction in which the container 1 is transported. For this reason, the control of the scanning in the A direction by the galvanometer mirror 221 needs to be determined taking into consideration the transport speed at which the container 1 is transported in the A direction.

Figure 5 shows the irradiation area of laser light according to one embodiment of the present invention.

In the following, Figure 5 explains a container 1 that is a PET bottle with ribs as an example of an irradiation area, and the explanation of the contents that overlap with the explanation of Figure 3 will be omitted as appropriate.

Figure 5 (a) shows an example of forming a pattern 401 by irradiating a laser beam 202 onto an irradiated surface 400. While conveying a plastic bottle in the A direction, the laser irradiation device 200 scans the laser beam 202 in the A direction using a galvanometer mirror 221, and also scans the laser beam 202 in the C direction using a polygon mirror 231. This allows the laser beam 202 to be irradiated to any position on the irradiated surface 400.

Figure 5 (b) shows irradiation areas on the irradiated surface 400 where the laser light 202 is irradiated, and non-irradiation areas where the laser light 202 is not irradiated. When a ribbed plastic bottle is used as the container 1, an example is shown in which convex parts and concave parts are alternately included. The convex parts are suitable as areas to be irradiated with the laser light 202, and the concave parts are not suitable as areas to be irradiated with the laser light 202. Therefore, the convex parts are considered as irradiation areas to be irradiated with the laser light 202, and the concave parts are considered as non-irradiation areas to be irradiated with the laser light 202.

In FIG. 5(b), irradiated and non-irradiated regions are formed alternately. A non-irradiated region (1-2) is present between irradiated region (1) and irradiated region (2), and a non-irradiated region (2-3) is present between irradiated region (2) and irradiated region (3).

Below, we will explain in detail how to improve productivity and ensure irradiation accuracy when irradiating the irradiation area.

Figure 6 shows the relationship between the scanning speed (v) of the laser light and time (t) in one embodiment of the present invention.

Figure 6(a) is a diagram showing the relationship between the scanning speed (v) of a typical laser beam and time (t). Figure 6(b) is a diagram showing the relationship between the scanning speed (v) of the laser beam and time (t) when a PET bottle with ribs is irradiated with a laser in a comparative example. Figure 6(c) is a diagram showing the relationship between the scanning speed (v) of the laser beam and time (t) in the present invention.

In Figure 6(a), the scanning speed (v) of the laser light is first accelerated in the section t(0-1) and reaches a speed v1. Thereafter, the scanning speed (v) of the laser light is kept constant at the speed v1 in sections t(1), t(1-2), t(2), and t(3). After the end of section t(3), the speed is decelerated to zero in the section from t(1) to t(3). In this way, it is common for the scanning speed (v) of the laser light to be constant in the irradiation area during one scanning line.

In FIG. 6(b), as in FIG. 6(a), the scanning speed (v) of the laser light is accelerated in the section t(0-1) and reaches a speed v1. Thereafter, the scanning speed (v) of the laser light is kept constant at a speed v1 in sections t(1), t(1-2), t(2), and t(3). After the end of section t(3), the speed is decelerated to zero in the section from t(1) to t(3).

For this reason, the container 1 shown in Figure 5 includes irradiated and non-irradiated areas. Therefore, it is necessary to control the irradiation of the laser light.

Distances A, B, and C in Figure 6(b) represent the distances scanned by the laser light in irradiated area (1), irradiated area (2), and irradiated area (3), respectively. For example, the total distance scanned while irradiating irradiated area (1) with the laser light is represented by the area (= distance A) enclosed by the scanning speed v1 of the laser light and the scanning time t(1) during that time. Regardless of whether the area is irradiated or not, scanning is performed at a constant speed of v1 in the sections t(1), t(1-2), t(2), and t(3).

In contrast, in FIG. 6(c), when scanning two or more irradiation areas and a non-irradiation area sandwiched between the irradiation areas using the irradiation of laser light as control, scanning is performed at a constant speed in the irradiation areas, and the scanning speed is changed in the non-irradiation areas. Specifically, in the non-irradiation area (1-2) in FIG. 6(c), the scanning speed of the laser light is accelerated at acceleration a. Due to this acceleration, the scanning speed in the irradiation area (2) reaches v2.

The distance irradiated by laser scanning is expressed as speed x time, but compared to Figure 6(b), in Figure 6(c) a greater distance is scanned by "distance D" during the same scanning time t(2) in the irradiation area (2).

Figures 6(b) and 6(c) are compared under the assumption that the total scanning time is constant, meaning that within a given time, Figure 6(c) can scan a greater distance than Figure 6(b).

In other words, if the total scanning distance is the same in Figure 6(b) and Figure 6(c), the total scanning time is shorter in Figure 6(c) than in Figure 6(b), improving productivity.

Figure 6 is a graph showing the progression of the scanning speed for one line, so the assumption is that the speed is zero when the scan begins, and is also zero when the scan ends.

In FIG. 6(c), the laser accelerates at the highest possible acceleration a after scanning starts, and then accelerates at the acceleration a in the next non-irradiated area (1-2), repeating this process. There is no limit to the number of non-irradiated areas in this case.

Then, in the non-illuminated area (e.g., non-illuminated area (2-3)), the speed is decelerated, and finally, at the end of one line, the speed becomes zero.

In this case, the total scanning time is the shortest and productivity is improved the most.

In other words, if we assume that the irradiation area with the fastest scanning speed (e.g., irradiation area (2) in FIG. 6(c)) is the specific irradiation area, the scanning speed of the irradiation area scanned before the specific irradiation area (e.g., irradiation area (1) in FIG. 6(c)) will be slower than the scanning speed of the specific irradiation area, and the scanning speed of the irradiation area scanned after the specific irradiation area (e.g., irradiation area (3) in FIG. 6(c)) will be slower than the scanning speed of the specific irradiation area.

Such variations in scanning speed (speed profile) within a line result in maximum productivity.

Here, any method may be used to irradiate the irradiation area with laser light or not irradiate the non-irradiation area with laser light. For example, the pulse laser 21 may switch between irradiating and not irradiating based on a change in the scanning speed within the irradiation area. Also, for example, even if the laser itself emits laser light continuously, it may be possible to switch between irradiating and not irradiating at blocking intervals using a shutter or the like that blocks the laser light.

Next, we will explain how to ensure irradiation accuracy.

In both Figure 6(b) and Figure 6(c), the scanning speed in the irradiation area is constant.

This is because marking when accelerating and decelerating during irradiation is more likely to result in larger position errors than marking during constant speed scanning.

In the present invention, the laser light does not accelerate or decelerate in the irradiated area, but only in the non-irradiated area, ensuring the accuracy of the laser light irradiation.

In other words, by ensuring the accuracy of laser light irradiation without accelerating or decelerating in the irradiated area, while accelerating or decelerating only in the non-irradiated area, it is possible to simultaneously achieve improved productivity.

Regarding the acceleration of the laser light scanning speed, it has been found that rapid acceleration and deceleration during laser light scanning makes it easier to excite resonance.

In general, the maximum acceleration value at which resonance does not occur during acceleration/deceleration is determined based on the scanning mechanism that scans the laser light and its control means, etc.

Therefore, in order to maximize productivity while ensuring the accuracy of laser light irradiation, the acceleration in the non-irradiated areas should be maximized without accelerating or decelerating in the irradiated areas.

In the present invention, the speed is controlled to maximize productivity while ensuring the accuracy of laser light irradiation.

We also explain how maximum productivity can be achieved by scanning a single line by accelerating the scan from a zero speed, irradiating, and then returning the speed to zero to end the scan.

The maximum acceleration value at which resonance does not occur during acceleration/deceleration is determined based on the scanning mechanism that scans the laser light and its control means, etc.

For this reason, in order to increase overall productivity, it is necessary to accelerate at the maximum acceleration at which resonance does not occur in the non-irradiated area, for example as shown in Figure 6 (c), and then accelerate at the maximum acceleration at which resonance does not occur again in the next non-irradiated area.

Also, the scanning speed must be zero when the scan ends.

For this reason, for example, if the area of maximum speed in the irradiation area (2) in Figure 6 (c) is taken as the specific irradiation area, the scanning speed of the irradiation area scanned before the specific irradiation area must be slower than the scanning speed of the specific irradiation area, and the scanning speed of the irradiation area scanned after the specific irradiation area must be slower than the scanning speed of the specific irradiation area.

The relationship between the scanning speed (v) of the laser light and time (t) inevitably becomes hill-shaped, as shown in Figure 6 (c).

Figure 7 shows an example of the application of acceleration and deceleration in illuminated and non-illuminated areas according to one embodiment of the present invention.

In Fig. 7(a), the irradiated area is not accelerated or decelerated, but the non-irradiated area is accelerated or decelerated. In Fig. 7(b), part of the non-irradiated area is scanned at a constant speed without acceleration or deceleration. In Fig. 7(c), part of the irradiated area is accelerated or decelerated without being scanned at a constant speed.

Figure 7(a) is the same as Figure 6(c), and does not accelerate or decelerate in the illuminated area, but accelerates or decelerates only in the non-illuminated area. Figure 7(a) is the same as Figure 6(c), and does not accelerate or decelerate in the illuminated area, but accelerates or decelerates only in the non-illuminated area.

Figures 7(a) and 7(b) show different controls in sections (E) and (G), which are the non-illuminated areas adjacent to the illuminated area.

The speed is constant in the non-illuminated area in the section (E) just before the non-illuminated area is reached from the non-illuminated area to the illuminated area. The speed is also constant in the non-illuminated area in the section (G) just after the non-illuminated area is reached from the illuminated area.

In this way, by setting the scanning speed in the certain sections (E) and (G), which are part of the non-irradiated area before and after the irradiated area, to be the same as the scanning speed in the section (F), which is the irradiated area, the irradiation accuracy in the irradiated area becomes more stable.

Even if resonance does occur, there is an advantage in that it allows time for the resonance to subside, making it possible to perform reliable constant-speed scanning in the irradiation area.

In this way, in order to prevent resonance in the non-irradiated area, the acceleration and deceleration in the non-irradiated area is set within a range that does not excite resonance, but by setting the scanning speed to the same as the irradiated area in some sections of the non-irradiated area before and after the irradiated area, more stable constant-speed scanning is possible in the irradiated area.

Figures 7(a) and 7(c) show different controls in sections (H) and (J), which are the illuminated areas adjacent to the non-illuminated areas.

Acceleration and deceleration occur in the non-illuminated area in the section (H) shortly after the non-illuminated area is reached from the non-illuminated area to the illuminated area. Acceleration and deceleration also occur in the non-illuminated area in the section (J) shortly before the non-illuminated area is reached from the illuminated area.

Figure 7(c) shows that productivity can be improved compared to Figure 7(b) by setting a different scanning speed in certain sections (H) and (J) that are part of the irradiated area before and after the non-irradiated area from the scanning speed in section (I) of the irradiated area, which is a constant speed.

In many cases, sections (H) and (J) that are close to the edge of the irradiation area are not sections (I) that are originally planned for irradiation, but are set as margins for adjusting the irradiation position. In this case, since irradiation is not planned for the blank sections, there are no problems with irradiation accuracy even if the machine is accelerated or decelerated. In this way, productivity can be improved while maintaining stable irradiation accuracy.

The scanning control and irradiation control of the laser light are controlled by a control unit 6 included in the laser irradiation device 200. The hardware configuration and functional configuration of the control unit 6 will be described with reference to Figs. 8 and 9.

Figure 8 is a block diagram showing the hardware configuration of a control unit according to one embodiment of the present invention. Figure 9 is a block diagram showing the functional configuration of a control unit according to one embodiment of the present invention. It is not necessary for all of the hardware and functional configurations that make up the control unit 6 to be provided. Depending on the form in which the laser irradiation device 200 is used, some hardware and functional configurations may not be provided. In addition, all of the hardware and functional configurations of the control unit may be provided in the laser irradiation device 200, or some of the hardware and functional configurations may be connected outside the laser irradiation device 200. Furthermore, the control unit 6 may be connected outside the laser irradiation device 200.

<Hardware configuration of control unit 6>
The control unit 6 is constructed as a computer or a configuration equivalent to a computer.

The control unit 6 shown in FIG. 8 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, a HD (Hard Disk) 504, a HDD (Hard Disk Drive) controller 505, and a display 506. The control unit 6 also includes an external device connection I/F (Interface) 508, a network I/F 509, a bus line 510, a keyboard 511, a pointing device 512, a DVD-RW (Digital Versatile Disk Rewritable) drive 514, and a media I/F 516.

The CPU 501 is a processor that controls the operation of the entire control unit 6. The ROM 502 is a memory that stores programs used to drive the CPU 501, such as an IPL (Initial Program Loader).

RAM 503 is a memory used as a work area for CPU 501. HD 504 is a memory that stores various data such as programs. HDD controller 505 controls the reading and writing of various data from HD 504 under the control of CPU 501.

The display 506 displays various information such as a cursor, a menu, a window, text, or an image. The external device connection I/F 508 is an interface for connecting various external devices. In this case, the external devices are the pulse laser 21, the scanning unit 23, the synchronization detection unit 25, the rotation mechanism 3, the movement mechanism 4, and the dust collection unit 5. However, other devices such as a USB (Universal Serial Bus) memory or a printer can also be connected.

The network I/F 509 is an interface for data communication using a communication network. The bus line 510 is an address bus, a data bus, etc. for electrically connecting each component such as the CPU 501.

The keyboard 511 is a type of input means equipped with multiple keys for inputting characters, numbers, various instructions, etc. The pointing device 512 is a type of input means for selecting and executing various instructions, selecting a processing target, moving the cursor, etc.

The DVD-RW drive 514 controls the reading and writing of various data from a DVD-RW 513, which is an example of a removable recording medium. Note that this is not limited to a DVD-RW, and may be a DVD-R or the like. The media I/F 516 controls the reading and writing (storing) of data from a recording medium 515, such as a flash memory.

All of these pieces of hardware that make up the control unit 6 do not necessarily have to be provided. Depending on the form in which the laser irradiation device 200 is used, some of the hardware may not be provided.

<Functional configuration of control unit 6>
Next, the functional configuration of the control unit 6 will be described.

The control unit 6 shown in FIG. 9 includes an irradiation data input unit 61, a profile data designation unit 62, a storage unit 63, a control data generation unit 64, a laser irradiation control unit 65, and a laser scanning control unit 66.

The functions of the control data generation unit 64, the laser irradiation control unit 65, and the laser scanning control unit 66 are realized by the CPU 501 executing a predetermined program and outputting a control signal via the external device connection I/F 508, etc. However, some or all of the functions of each component may be realized by electronic or electric circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) by adding them to the hardware configuration of the control unit 6. The function of the storage unit 63 is realized by the HD 504, etc.

The irradiation data input unit 61 inputs irradiation data for irradiating the irradiated surface 400 of the container 1 from an external device such as a PC (Personal Computer) or a scanner. The irradiation data may be something other than the irradiation pattern. It may be information indicating a predetermined code such as a barcode or QR code (registered trademark) or a pattern of characters, figures, photographs, etc., that corresponds to the irradiation pattern.

However, the pattern data to be irradiated is not limited to data input from an external device. The user of the laser irradiation device 200 can also input the generated pattern data to be irradiated using the keyboard 511 or pointing device 512 of the control unit 6.

The irradiation data input unit 61 outputs the input irradiation data to each of the control data generation unit 64 and the profile data designation unit 62. The irradiation data input from the irradiation data input unit 61 may be temporarily stored in the storage unit 63. Since the irradiation data differs depending on the shape of the container 1, etc., irradiation data corresponding to the type of container 1 may be stored in advance in the storage unit 63 to improve convenience.

The profile data specification unit 62 specifies the profile data.

The profile data referred to here determines the irradiated and non-irradiated areas when irradiating the laser light while scanning, and also determines the acceleration, acceleration/deceleration period, and constant speed period when accelerating the scanning speed.

The profile data is also stored in the storage unit 63. The profile data may be stored in advance, or may be stored as a temporary storage means during scanning and irradiation.

The control data generation unit 64 generates control data based on the irradiation data from the irradiation data input unit 61 and the profile data from the profile data specification unit 62.

In addition, the control data generation unit 64 outputs the generated control data to the laser irradiation control unit 65 and the laser scanning control unit 66.

The laser irradiation control unit 65 includes a light intensity control unit 651 and a pulse control unit 652, and controls the irradiation of the laser light 202 by the pulse laser 21 onto the container 1 based on the irradiation condition data.

The laser scanning control unit 66 also controls the scanning unit 23 based on the synchronization detection signal from the synchronization detection unit 25.

When the pulse laser 21 is composed of a plurality of pulse lasers, the laser irradiation control unit 65 controls each of the plurality of pulse lasers independently.

The light intensity control unit 651 controls the light intensity of the processing laser beam 20 , and the pulse control unit 652 controls the pulse width and irradiation timing of the processing laser beam 20 .

The laser scanning control unit 66 controls the scanning of the galvanometer mirror 221 and the polygon mirror 231 by the scanning unit 23 based on the scanning condition data. Specifically, it controls the on/off driving of the galvanometer mirror 221 and the polygon mirror 231, controls the driving frequency, etc.

Figure 10 shows an acceleration/deceleration trajectory for suppressing excitation of resonance during acceleration/deceleration in one embodiment of the present invention.

Figure 10(a) is a diagram explaining acceleration and deceleration using an S-curve. In Figure 10(a), in one acceleration and deceleration region connecting two constant speed regions, the scanning speed of the scanning means is changed along a smooth curved S-curve as an S-curve acceleration and deceleration trajectory. This allows acceleration and deceleration to be performed gently, suppressing the excitation of resonance during acceleration and deceleration.

As an example, the shape of the S-curve can be determined by the following formula:

Here, v(t) is the scanning speed at time t during acceleration/deceleration, v0 is the scanning speed at a constant speed before the acceleration/deceleration, v1 is the amount of speed change from v0 due to the acceleration/deceleration, and k is a value determined by the time required for the acceleration/deceleration. Note that in the above formula, the start of acceleration/deceleration is defined as t=0, and the end of acceleration/deceleration is defined as t=0.5k.

However, this formula is just an example, and other formulas may be applied as appropriate.

Figure 10(b) is a diagram explaining acceleration and deceleration using a resonant filter.

In Figure 10(b), as an example, a notch filter, which is a type of resonant filter, is used to create an acceleration/deceleration trajectory and change the scanning speed of the scanning means. In an acceleration/deceleration trajectory using this resonant filter (hereinafter referred to as a "resonant filter acceleration/deceleration trajectory"), resonance is cancelled out, and the speed changes while exhibiting a wavy behavior during acceleration/deceleration.

Note that there are other resonant filters besides notch filters that can be used to create the resonant filter acceleration/deceleration trajectory, and there are no limitations on the type or number of filters used.

Figure 11 is a diagram showing a first example of a configuration for forming a laser light intensity profile and processing marks using a pulsed laser according to one embodiment of the present invention. This shows the laser light intensity profile and processing mark formation results when using a pulsed laser without changing the laser pulse frequency according to the scanning speed.

Figure 11 (a) shows a case where the scanning speed in irradiation area (1) and irradiation area (2) is constant, and the scanning speed in irradiation area (1) and irradiation area (2) is different.

Figure 11 (b) shows the state where the laser pulse frequency is not changed in irradiation area (1) and irradiation area (2). When laser pulses are emitted at a constant frequency in this way, regardless of the scanning speed, the spatial spacing of the machining marks formed when the scanning speed is slow and fast will differ, as shown in Figure 11 (c). When the pulse frequency is fixed, the faster the scanning speed, the coarser the machining marks will be formed.

Figure 12 is a diagram showing a second example of the configuration of the laser light intensity profile and the formation of processing marks by a pulsed laser according to one embodiment of the present invention. This shows the laser light intensity profile and the results of the formation of processing marks when the laser pulse frequency is changed according to the scanning speed when using a pulsed laser.

Figure 12 (a) shows a case where the scanning speed in irradiation area (1) and irradiation area (2) is constant, and the scanning speed in irradiation area (1) and irradiation area (2) is different.

If you want to always create machining marks at regular intervals, you can adjust the pulse frequency according to the scanning speed as shown in Figure 12 (b), and you can create machining marks at regular intervals regardless of the scanning speed as shown in Figure 12 (c).

When the scanning speed is constant, the laser pulse frequency is set according to the following formula.

Here, f is the laser pulse frequency, v is the scanning speed at the corresponding constant speed state, and p is the interval between the processing marks you want to form. However, if processing marks are to be formed during acceleration/deceleration, the above formula does not apply. In this case, based on the laser spot position at each time predicted from the default scanning speed profile, the laser pulse frequency is changed so that the laser pulse is emitted at the time the laser spot is scheduled to pass the position closest to the position where each of the target processing marks is to be formed.

Instead of changing the laser pulse frequency, a laser with a high original laser pulse frequency may be used, and the frequency of the emitted laser pulse may be effectively changed by repeatedly opening and closing an electronically controlled shutter.

Figure 13 is a diagram showing a first example of a configuration for forming a laser light intensity profile and processing marks using a CW laser according to one embodiment of the present invention. This shows the laser light intensity profile and processing mark formation results when using a CW laser without changing the laser light intensity according to the scanning speed.

Figure 13 (a) shows the state where the scanning speed in the irradiation area (1) is v1, and the scanning speed in the irradiation area (2) is v2.

When laser light is emitted at a constant intensity regardless of the scanning speed as in Figure 13(b), the line width of the processed mark will differ when the scanning speed is slow and fast as in Figure 13(c). When the light intensity is fixed, the faster the speed, the thinner the processed mark will be.

Figure 14 shows a second example of the configuration for the laser light intensity profile and the formation of processing marks using a CW laser according to one embodiment of the present invention. This shows the laser light intensity profile and the results of the formation of processing marks when the laser light intensity is changed according to the scanning speed when using a CW laser.

Figure 14 (a) shows the state where the scanning speed in the irradiation area (1) is v1, and the scanning speed in the irradiation area (2) is v2.

If you want to always create a constant line width for the processed mark, you can adjust the light intensity according to the scanning speed as shown in Figure 14(b), and you can create a constant line width for the processed mark regardless of the scanning speed as shown in Figure 14(c).

Generally, the relationship between light intensity and scanning speed varies depending on processing conditions such as the physical properties of the material being processed, but generally there is a proportional relationship between light intensity and scanning speed.

Figure 15 is a flowchart for generating a scanning speed profile according to one embodiment of the present invention.

This scanning speed profile generation is mainly performed by the control data generation unit 64.

First, irradiation data is input to the control unit 6 (S100).

Next, the input data is divided into each scan line (S101). This is to determine how to accelerate and decelerate in accordance with the illuminated and non-illuminated areas within each scan line.

Next, it is determined whether or not there is a non-irradiated area in the one scanning row pattern (S102). If the input data is a bitmap image, if there is one or more blank dots, it is determined that there is a non-irradiated area in the one scanning row pattern. If there is a non-irradiated area, proceed to S103. If there is no non-irradiated area, proceed to S114. The entire row is treated as a single constant speed area, and a speed profile consisting of a constant speed scanning speed and acceleration and deceleration before and after it is determined (S114).

Next, each of the adjacent non-illuminated regions after connection is defined as a non-illuminated region (S103).

It is determined whether the length of one non-irradiated area is equal to or greater than threshold L (S104). The threshold L for determining the length of this non-irradiated area is determined by a predefined upper limit of the optical scanner acceleration. If the length of one non-irradiated area is equal to or greater than threshold L, proceed to S105. If the length of one non-irradiated area is not equal to or greater than threshold L, proceed to S106.

If it is equal to or greater than the threshold L, acceleration/deceleration is possible, so the non-illuminated area is defined as the area in which acceleration/deceleration is performed (S105).

Similarly, it is determined whether the length has been evaluated for all non-irradiated areas (S106). If the length has been evaluated for all non-irradiated areas, proceed to S107. If the length has not been evaluated for all non-irradiated areas, return to S104.

When the length has been evaluated for all non-irradiated areas, the area other than the non-irradiated area of the one scanning row pattern is defined as the irradiated area (S107).

Next, the number of non-irradiated areas for which acceleration is to be performed in one scanning row pattern is calculated (S108).

It is determined whether there are two or more non-illuminated regions in which acceleration/deceleration is performed within one scanning row pattern (S109). If there are two or more illuminated regions, proceed to S110. If there are no illuminated regions, proceed to S114.

If there are two or more non-irradiated areas that undergo acceleration/deceleration, a constant velocity area and the acceleration/deceleration areas immediately before and after it are assigned to each irradiation, and the remaining acceleration/deceleration areas are assigned to the non-irradiated areas (S110).

Calculate the achievable speed change by accelerating and decelerating in each acceleration/deceleration region (S111).

A speed profile consisting of the speed of each constant speed region and the acceleration/deceleration speeds before and after each constant speed region is determined for the entire row, within the speed change limit and shortening the scanning time for one row (S112).

Determine whether the speed profiles for all columns have been determined (S113). If they have not been determined, return to S102. If they have been determined, end the process.

In the embodiment, it is assumed that all non-irradiated areas in the pattern data where acceleration and deceleration are performed are the same length. If the length of each non-irradiated area varies depending on the position in the pattern data, an acceleration/deceleration profile for the non-irradiated area is calculated appropriately according to the lengths, or table data is applied as the profile appropriately.

Figure 16 shows the change in properties of the base material of a container according to one embodiment of the present invention.

<Examples of changes in the properties of the substrate>
Next, the change in properties of the base material of the container 1 caused by irradiation with the laser beam 202 will be described.

Figure 16(a) shows a recess shape formed by evaporating the base material on the surface of the container 1, and Figure 16(b) shows a recess shape formed by melting the base material on the surface of the container 1. In the case of Figure 16(b), the periphery of the recess is raised compared to Figure 16(a).

Figure 16(c) shows the change in the crystallization state on the surface of the substrate of container 1, and Figure 16(d) shows the change in the foaming state inside the substrate of container 1.

In this way, by changing the shape of the surface of the container 1, or by changing the properties such as the crystallization state of the substrate surface or the foaming state inside the substrate, a first pattern composed of an aggregate of second patterns can be formed on the surface or inside the container 1.

As a method for evaporating the base material on the surface of the container 1 to form a recessed shape, for example, a pulsed laser with a wavelength of 355 nm to 1064 nm and a pulse width of 10 fs to 500 ns or less is irradiated. This causes the base material in the area irradiated with the laser beam to evaporate, forming minute recesses on the surface.

It is also possible to melt the substrate and form recesses by irradiating it with a CW laser with a wavelength of 355 nm to 1064 nm. Furthermore, if the laser continues to be irradiated even after the substrate has melted, the inside and surface of the substrate can be foamed and clouded.

To change the crystallized state, for example, the substrate can be made of polyethylene terephthalate (PET), and a CW laser with a wavelength of 355 nm to 1064 nm can be irradiated to raise the temperature of the substrate in one go, and then the substrate can be gradually cooled by reducing the power, etc., to bring the PET substrate into a crystallized state and make it opaque. Note that if the substrate is cooled rapidly by turning off the laser beam after the temperature has been raised, the PET will become amorphous and transparent.

The change in the base material properties of the container 1 is not limited to that shown in FIG. 16. The properties of the base material may be changed by yellowing of the base material made of a resin material, oxidation reaction, surface modification, etc.

(Application example of the present invention)
The laser irradiation device 200 of the present invention can also be applied to a method for producing a three-dimensional object and a three-dimensional object forming device.

For example, powder bed fusion is known as one method for creating three-dimensional objects.

The powder bed fusion method is a method of forming a three-dimensional object by irradiating a laser on the powder to melt and bond it. Specifically, first, the powder material is spread evenly to form a layer. Next, a laser is irradiated at a desired position on the layer to selectively sinter or melt the particles contained in the powder material to bond the particles (hereinafter, bonding of particles by sintering or melting is also simply referred to as "fusion bonding"). This forms one layer as a layer that divides the three-dimensional object in the thickness direction (hereinafter, simply referred to as "modeled object layer"). Further powder material is spread on the modeled object layer thus formed, and the next modeled object layer is formed by irradiating it with a laser. This procedure is repeated to stack the modeled object layers, and a three-dimensional object of the desired shape is manufactured. The powder material includes resin materials, metal materials, etc., and two or more types may be mixed as appropriate, and additives may be further added.

Figure 17 is a side view showing an example of the configuration of a three-dimensional modeling apparatus according to one embodiment of the present invention. The three-dimensional modeling apparatus 500 includes a modeling stage 310, a layer forming 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 adjusted. The modeling stage 310 is configured so that it can be precisely moved in the vertical direction by the stage support unit 350. Various configurations can be used 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.

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. The layer forming unit 320 includes, for example, an edge of an opening through which the modeling stage 310 rises and falls, an opening whose edge is on approximately the same plane in the horizontal direction, and a powder material storage unit that extends vertically downward from the opening. The powder supplying unit 321 also 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 supply unit 321 may also be configured to include a powder material storage unit disposed vertically above the modeling stage 310, and a nozzle, and to eject the powder material on the same plane horizontally as the modeling stage.

The preheating unit 330 preheats the layer formed by the layer forming unit 320. It is sufficient that the preheating unit 330 can heat at least the area of the surface of the layer where the model layer is to be formed and maintain that temperature. 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 to the modeling stage. The preheating unit 330 may be configured to selectively heat the area where the model 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.

The first heater 331 may be a heater 331a that heats the layer from the top, a heater 331b that heats the layer from the side, or a 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 further away from the first heaters 331a, 331b, and 331c. Therefore, from the viewpoint of making it difficult for temperature unevenness to occur on the surface of the layer and making it difficult for deformation of the model layer due to temperature unevenness on the surface of the layer to occur, it is preferable that the first heater 331 includes a plurality of heaters that are arranged separately from each other. In this case, it is preferable that the first heaters 331a arranged in a plurality of positions, the first heaters 331b arranged in a plurality of positions, and the first heaters 331c arranged in a plurality of positions are arranged at equal intervals from each other.

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, for example an infrared sensor or an optical pyrometer.

The laser irradiation device 200 irradiates the layer with a laser. A modeled object layer is formed by irradiating the laser. The laser irradiation device 200 includes a pulsed laser 21 and a galvanometer mirror 221. The pulsed laser 21 may be a CW laser. The galvanometer mirror 221 reflects the laser emitted from the pulsed laser 21 and scans the laser. The laser irradiation device 200 may include a laser window 343 that transmits the laser. The laser window 343 may be made of any material that transmits the laser.

In the 3D modeling device 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, resulting in a decrease in the accuracy of the 3D model.

Therefore, the temperature is measured using the temperature measuring device 335, and the energy of the laser irradiated by the laser irradiation device 200 is adjusted according to the temperature result.

Specifically, when the preheating temperature is low, the energy given from the laser to the particles in the irradiated area is increased, and when the preheating temperature is high, the energy given from the laser to the particles in the irradiated area is reduced.

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 due to the laser irradiation, the laser irradiation device 200 controls the energy due to the laser irradiation that the particle receives per unit time by changing the scanning speed of the laser scan.

In the laser irradiation device 200 of the present invention, the scanning speed can be precisely controlled for each irradiation area, so the laser energy applied 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.

●Summary

<1> A laser irradiation device 200 according to one embodiment of the present invention is a laser irradiation device including an irradiation means for irradiating laser light and a scanning means for scanning the laser light irradiated by the irradiation means, and includes a control unit 6 for controlling the irradiation means and the scanning means so that when the scanning means scans two or more irradiation areas and non-irradiation areas sandwiched between the irradiation areas, the irradiation areas are scanned at a constant speed and the scanning speed is changed in the non-irradiation areas.

This allows the laser irradiation device 200 to ensure laser irradiation accuracy while simultaneously improving productivity.

<2> In the above <1>, in the laser irradiation device 200 according to one embodiment of the present invention, the control unit 6 controls the scanning speed of the non-irradiated area adjacent to the irradiated area so that it is the same as the scanning speed of the irradiated area.

This allows the laser irradiation device 200 to ensure even higher accuracy in laser irradiation.

<3> In the above <1>, in the laser irradiation device 200 according to one embodiment of the present invention, the control unit 6 controls the scanning speed of the portion of the irradiation area adjacent to the non-irradiation area to be changed.

This allows the laser irradiation device 200 to ensure even higher productivity in laser irradiation.

<4> In the above items <1> to <3>, in the laser irradiation device 200 according to one embodiment of the present invention, the control unit 6 controls the scanning speed of the irradiation area scanned before the specific irradiation area to be slower than the scanning speed of the specific irradiation area, and controls the scanning speed of the irradiation area scanned after the specific irradiation area to be slower than the scanning speed of the specific irradiation area.

This makes it possible to ensure irradiation accuracy across multiple irradiation areas and the non-irradiated areas between them, while at the same time maximizing productivity.

<5> In the above items <1> to <4>, in the laser irradiation device 200 according to one embodiment of the present invention, the control unit 6 controls the change in the scanning speed of the scanning means so as to form an S-shaped acceleration/deceleration trajectory.

This makes it possible to prevent resonance and ensure irradiation accuracy when changing the scanning speed.

<6> In the above items <1> to <4>, in the laser irradiation device 200 according to one embodiment of the present invention, the control unit 6 controls the change in the scanning speed of the scanning means so as to obtain a resonant filter acceleration trajectory.

This makes it possible to prevent resonance and ensure irradiation accuracy when changing the scanning speed.

<7> In the above items <1> to <4>, in the laser irradiation device 200 according to one embodiment of the present invention, when the irradiation means is a pulsed laser, the control unit 6 controls the change in the interruption interval of the pulsed laser based on the change in the scanning speed within the irradiation area.

As a result, when the scanning speed is changed, the pulse frequency can be adjusted according to the scanning speed to keep the interval between pulse irradiation constant and ensure irradiation accuracy.

<8> In the above items <1> to <4>, in the laser irradiation device 200 according to one embodiment of the present invention, when the irradiation means is a CW laser, the control unit controls the output of the CW laser to be changed based on the change in the scanning speed within the irradiation area.

As a result, when the scanning speed is changed, the light intensity can be adjusted according to the scanning speed to keep the line width of the processing marks constant and ensure irradiation accuracy.

<9> The irradiation method using the laser irradiation device 200 according to one embodiment of the present invention includes an irradiation step of irradiating laser light, a scanning step of scanning the laser light irradiated by the irradiation means, and a control step of controlling the scanning means so that when the scanning means scans two or more adjacent irradiation areas and the non-irradiation areas sandwiched therebetween, the scanning speed is constant within the irradiation areas and the scanning speed is changed within the non-irradiation areas.

This allows the laser irradiation device 200 to ensure laser light irradiation accuracy while simultaneously improving productivity.

REFERENCE SIGNS LIST 1 container 200 laser irradiation device 202 laser light 21 pulsed laser 22 beam expander 221 galvanometer mirror 23 scanning unit 231 polygon mirror 241 fθ lens 25 synchronous detection unit 251 LD for synchronous detection
252 Synchronous detection PD
300 Transport detection unit 301 Transport detection light emitting element 302 Transport detection light receiving element 310 Modeling stage 320 Layer forming unit 321 Powder supply unit 322a Recoater 330 Preheating unit 331, 331a, 331b, 331c First heater 332 Second heater 335 Temperature measuring device 343 Laser window 350 Stage support unit 400 Irradiated surface 401 Two-dimensional pattern 500 Three-dimensional modeling device 501 CPU
502 ROM
503 RAM
504 HD
505 HDD controller 506 Display 508 External device connection I/F
509 Network I/F
510 Bus line 511 Keyboard 512 Pointing device 513 DVD-RW
514 DVD-RW drive 515 Recording media 516 Media I/F
6 Control unit 61 Irradiation data input unit 62 Profile data designation unit 63 Storage unit 64 Control data generation unit 65 Laser irradiation control unit 651 Light intensity control unit 652 Pulse control unit 66 Laser scanning control unit
A Conveying direction
B Galvano mirror oscillation direction
C C direction
D D direction Lx Size of the pattern in the transport direction Lz Size of the pattern in the cross direction

US10583668

Claims (9)

An irradiation means for irradiating a laser beam;
a scanning means for scanning the laser light irradiated by the irradiating means;
In a laser irradiation device comprising:
When the scanning means scans two or more irradiation areas and a non-irradiation area sandwiched between the irradiation areas,
A laser irradiation device having a control unit that controls the irradiation means and the scanning means so as to scan at a constant speed within the irradiation region and to change the scanning speed within the non-irradiation region. In the laser irradiation device of claim 1,
The laser irradiation device according to claim 1, wherein the control unit controls a scanning speed of a portion of the non-irradiated region adjacent to the irradiated region so as to be equal to a scanning speed of the irradiated region. In the laser irradiation device of claim 1,
The laser irradiation device, wherein the control unit controls so as to change a scanning speed of a portion of the irradiation area adjacent to the non-irradiation area. In the laser irradiation device according to any one of claims 1 to 3,
The control unit controls the scanning speed of an irradiation area scanned before a specific irradiation area to be slower than the scanning speed of the specific irradiation area, and controls the scanning speed of an irradiation area scanned after the specific irradiation area to be slower than the scanning speed of the specific irradiation area. The laser irradiation device according to any one of claims 1 to 3,
The laser irradiation device, wherein the control unit controls the change in the scanning speed of the scanning means so as to form an S-shaped acceleration/deceleration trajectory. The laser irradiation device according to any one of claims 1 to 3,
The laser irradiation device according to the present invention, wherein the control unit controls the change in the scanning speed of the scanning means so as to follow a resonance filter acceleration trajectory. In the laser irradiation device according to any one of claims 1 to 3,
When the irradiation means is a pulse laser, the control unit
A laser irradiation device characterized in that the interruption interval of the pulse laser is changed based on a change in a scanning speed within the irradiation area. In the laser irradiation device according to any one of claims 1 to 3,
When the irradiation means is a continuous wave laser, the control unit
A laser irradiation device characterized by controlling so as to change the output of the continuous wave laser based on a change in a scanning speed within the irradiation area. an irradiation step of irradiating with laser light;
a scanning step of scanning the laser light irradiated by the irradiation means;
When the scanning means scans two or more adjacent irradiation areas and non-irradiation areas sandwiched therebetween,
A laser irradiation method comprising a control step of controlling the scanning means so as to scan at a constant speed within the irradiation region and to change the scanning speed within the non-irradiation region.