Laser marking equipment

Abstract

To provide a laser marking device that can suppress reduction in light volume while preventing an optical component from being damaged in an optical system for scanning a plurality of laser beams with an identical optical system and condensing light.SOLUTION: A laser marking device processes an object by scanning a surface of the object with a plurality of laser beams using an identical scanning means and lens. The scanning means includes: first scanning means for scanning in a first direction; and a second scanning means for scanning in a direction substantially orthogonal to the first direction. The first scanning means is positioned in an optical path in which optical paths of the plurality of laser beams converge.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a laser marking device. Place Regarding. [Background technology]

[0002] Conventionally, containers such as polyethylene terephthalate (PET) bottles are known to have labels attached thereto indicating the name, ingredients, expiration date, barcode, and other images. Meanwhile, in recent years, there has been a worldwide movement to eliminate pollution caused by plastic waste, and the demand for closed-loop recycling of containers is increasing. Here, closed-loop recycling of containers refers to recycling companies turning used containers that have been separated and collected into flakes that are the raw material for containers, and remanufacturing containers.

[0003] In order to smoothly carry out this type of circular recycling, it is preferable to thoroughly separate and collect waste by material, such as containers or labels, but the task of removing labels from containers for separate collection is time-consuming, and is one of the constraints to thorough separate collection.

[0004] In contrast, methods of processing transparent objects such as transparent resins with laser light include, for example, processing with an infrared wavelength of 10.6 μm using a CO2 laser or the like, or processing with an ultraviolet wavelength of 355 nm. In processing using infrared wavelengths, the beam spot diameter cannot be narrowed sufficiently, so high-resolution drawing is achieved by narrowing the beam spot diameter using ultraviolet wavelengths. However, since pulse energy (average laser output determined by the repetition frequency) exceeding the processing threshold is required, a low frequency is required to obtain high pulse energy, and even if one dot can be processed with one pulse, productivity is highly dependent on the laser repetition frequency. On the other hand, a high frequency results in low pulse energy, so one dot cannot be processed with one pulse, and multiple pulses are required. As a result, the frequency required to form one dot becomes low, which is a problem in that it becomes difficult to increase productivity.

[0005] In order to solve the above problems, a laser processing device has been proposed that can increase processing speed while reducing costs and size by scanning and focusing multiple lasers with the same optical system and dividing the processing area according to the number of lasers installed.For example, a laser marking device has been proposed in which multiple beams are incident on an fθ lens at different angles of incidence using the same two-dimensional scanning means and fθ lens (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a laser marking device that can suppress a decrease in the amount of light while preventing damage to optical components in an optical system that scans and focuses multiple laser beams using the same optical system. [Means for solving the problem]

[0007] The laser marking device of the present invention as a means for solving the above problems is Laser marking is a method of processing an object by scanning the surface with multiple lasers using a scanning means and a lens. a scanning device, the scanning device comprising: a first scanning means for scanning in a first direction; and a second scanning means for scanning in a direction substantially perpendicular to the direction of the first scanning means. Located in the optical path where the optical paths of the multiple lasers converge The output of the plurality of lasers can be controlled in time, and the output timing of each laser is controlled to be shifted. do. Effect of the Invention

[0008] According to the present invention, it is possible to provide a laser marking device that can suppress a decrease in the amount of light while preventing damage to optical components in an optical system that scans and focuses a plurality of laser beams using the same optical system. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1A is a schematic diagram showing an example of a laser marking device according to a first embodiment. [Figure 1B] FIG. 1B is a schematic diagram showing another example of the laser marking device according to the first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the configuration of light beams produced by multiple lasers. [Figure 3A] FIG. 3A is a graph showing the relationship between the diameter of a beam incident on a scanning lens and the diameter of a beam spot on an image plane. [Figure 3B] FIG. 3B is a graph showing the relationship between the beam diameter incident on the scanning lens and the beam diameter deviation with respect to the beam waist diameter. [Figure 3C] FIG. 3C is a graph showing the relationship between the incident beam diameter and the beam diameter on the image plane. [Figure 4] FIG. 4 is a diagram for explaining the positional relationship between the effective radius and the beam spot diameter in the scanning means. [Figure 5A] FIG. 5A is a diagram for explaining the energy distribution in the scanning means, assuming that the laser intensity distribution can be approximated by a Gaussian distribution. [Figure 5B] FIG. 5B is a diagram for explaining the energy distribution in the scanning means, and actually includes a shift amount from the center of the scanning means. [Figure 6] 5 is a diagram for explaining the relationship between the beam radius and the effective radius with respect to the amount of positional deviation of the beam spot on the scanning means. FIG. [Figure 7] FIG. 7 is a diagram for explaining the energy distribution state when two beams are integrated. [Figure 8A] FIG. 8A is a diagram for explaining the relationship between the output timing of two lasers and the integrated energy, in the case where the output timings of the two lasers are synchronized. [Figure 8B] FIG. 8B is a diagram for explaining the relationship between the output timings of the two lasers and the integrated energy, in the case where the output timings of the two lasers are out of sync. [Figure 9]FIG. 9 is a diagram for explaining the relationship between the intersection angle of the two lasers and the maximum swing angle of the scanning means. [Figure 10A] FIG. 10A is a diagram for explaining the direction in which the two lasers are divided, in which the imaging area is divided in the horizontal direction relative to the container movement control direction. [Figure 10B] FIG. 10B is a diagram for explaining the direction in which the two lasers are divided, in which the imaging area is divided in a direction perpendicular to the container movement control direction. [Figure 11A] FIG. 11A is a schematic diagram showing an example of a laser marking device according to a modified example of the first embodiment. [Figure 11B] FIG. 11B is a diagram showing the direction of light rays as viewed from the direction A in FIG. 11A. [Figure 11C] FIG. 11C shows the spots on GM1 in FIG. 11A. [Figure 11D] FIG. 11D shows the spots on GM2 in FIG. 11A. [Figure 12A] FIG. 12A is a schematic diagram showing an example of a laser marking device according to the second embodiment. [Figure 12B] FIG. 12B is a schematic diagram showing another example of the laser marking device according to the second embodiment. [Figure 12C] FIG. 12C is a diagram for explaining the directions in which the three lasers are divided in the second embodiment, in which the imaging area is divided in the horizontal direction relative to the container movement control direction. [Figure 12D] FIG. 12D is a diagram for explaining the direction in which the three lasers are divided in the second embodiment, in which the imaging area is divided in a direction perpendicular to the container movement control direction. [Figure 13A] FIG. 13A is a schematic diagram showing an example of a laser marking device according to a third embodiment. [Figure 13B] FIG. 13B is a schematic diagram showing another example of the laser marking device according to the third embodiment. [Figure 13C]FIG. 13C is a diagram for explaining the directions in which the four lasers are divided in the third embodiment, in which the imaging area is divided in the horizontal direction relative to the container movement control direction. [Figure 13D] FIG. 13D is a diagram for explaining the directions in which the four lasers are divided in the third embodiment, in which the imaging area is divided in a direction perpendicular to the container movement control direction. [Figure 14A] FIG. 14A is a schematic diagram showing an example of a laser marking device according to a modified example of the third embodiment. [Figure 14B] FIG. 14B is a diagram for explaining directions in which the four lasers are split in the modified third embodiment. [Figure 15A] FIG. 15A is a scanning electron microscope photograph of a dot portion in a fine structure as a pattern, and is a perspective view seen from above. [Figure 15B] FIG. 15B is a scanning electron microscope photograph of a dot portion in a fine structure as a pattern, and is a perspective view seen from the cross-sectional direction of the arrow DD in FIG. 15A. [Figure 16] FIG. 16 is a schematic diagram showing a specific embodiment of a pattern on a container. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Laser marking device) The laser marking device of the present invention is a laser marking device in which multiple lasers scan and process the surface of an object using the same scanning means and lens, and the scanning means has a first scanning means for scanning in a first direction and a second scanning means for scanning in a direction approximately perpendicular to the first direction, and the first scanning means is positioned in the optical path where the optical paths of the multiple lasers converge.

[0011] In the conventional technique, Patent Document 1 (JP Patent Publication No. 11-156567), there is a problem that multiple laser beams overlap on an optical element, damaging the optical components. In addition, if the light beam layout is set so that the beams do not overlap on the optical components, there is a problem that the beam spot moves out of the effective range of the optical components, causing a decrease in the amount of light and making it impossible to process. In addition, in FIG. 1 of the above-mentioned JP Patent Publication No. 11-156567, the optical paths of multiple beams intersect on the near side of the scanning means, and the spacing between the optical paths becomes wider as the distance from the scanning means increases, and there is a problem that the scanning means becomes larger and the whole device becomes larger as the distance from the intersection position of the multiple optical paths increases.

[0012] In the present invention, unlike the above-mentioned conventional technology, by intersecting the lasers between the optical paths of the scanning means and shifting the multiple beams on the optical elements for multiple lasers and multiple scanning means, it is possible to suppress damage to the optical elements, and by minimizing the amount of positional deviation from the optical elements, it is possible to suppress a reduction in the amount of light caused by the beam spot moving out of the effective range of the optical components.

[0013] In one embodiment of the present invention, the intersection of the optical paths of the multiple lasers is between the first scanning means and the second scanning means. Therefore, the laser marking device can minimize the amount of beam spot positional deviation on the two scanning means, thereby suppressing the reduction in the amount of light due to light vignetting. According to this embodiment, when the laser marking device uses the same scanning means to print with multiple lasers, multiple areas can be drawn simultaneously, thereby improving productivity and saving space.

[0014] In one aspect of the present invention, it is preferable that the half angle θ1 [deg] of the intersection angle of the optical paths of the multiple lasers satisfies the following formula: 0.5 deg<θ1<29.5 deg. According to this aspect, the beam spots incident on the scanning lens do not overlap, so that damage to the scanning lens can be suppressed.

[0015] In one aspect of the present invention, it is preferable to satisfy the following formula: 1.22(b + x) < r. However, in the above formula, r represents the effective range of the optical element in the scanning means, b represents the laser spot radius, and x represents the shift amount of the laser spot from the center of the optical element in the scanning means. According to this aspect, it is possible to suppress a decrease in the amount of light on the optical element (for example, galvanometer mirror, polygon mirror) of the scanning means. Note that the coefficient 1.22 in the above formula is the case where an efficiency of 95% or more is achieved, and when an efficiency of 99% or more is achieved, the coefficient becomes 1.52.

[0016] In one aspect of the present invention, the movement of the object is controlled in the same direction as any of the scanning means. According to this aspect, by controlling the movement of the object in the same direction as any of the scanning means, it is possible to reduce the swing angle of the scanning means, and productivity can be improved.

[0017] In one aspect of the present invention, a configuration is provided in which a plurality of lasers can be output-controlled in time, and by controlling so as to shift the output timing of each laser, damage to the optical component can be suppressed.

[0018] In one aspect of the present invention, it is preferable to satisfy the following formula: θ1 < θ scan ,. However, in the above formula, θ1 represents the half angle of the intersection angle of the optical paths by a plurality of lasers, and θ scan represents the half angle of the maximum swing angle by the scanning means.

[0019] In one aspect of the present invention, a configuration is provided in which printing is performed on an object that is controlled to move in the same direction as any of the scanning means, and the optical paths of a plurality of lasers intersect in a direction that is substantially perpendicular to the direction of movement control and is divided in a direction perpendicular to the direction of movement control. According to this aspect, by dividing the drawing range (main division) in a direction that is substantially perpendicular to the movement control direction of the object to be printed, the scanning time in the main scanning direction can be shortened, and productivity can be improved.

[0020] Here, an embodiment of the laser marking device of the present invention will be described in detail with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated explanations may be omitted. In addition, the number, position, shape, etc. of the following components are not limited to the present embodiment, and may be the number, position, shape, etc. that are preferable for implementing the present invention.

[0021] <First embodiment of the laser marking device> 1A and 1B are schematic diagrams showing an example of a laser marking device 100 according to a first embodiment. The laser marking device 100 in Fig. 1A and 1B includes a laser light source unit, a scanning optical system unit 20, and a container conveying unit 21.

[0022] The laser light source unit to the scanning optical system unit 20 includes laser light sources 1a and 1b, beam expanders 2a and 2b, mirrors 3a and 3b, a lens 5, and synchronization detectors 8a and 8b. Here, examples of the mirrors 3a and 3b include rotating polygonal mirrors such as polygon scanners.

[0023] The laser light sources 1a and 1b are pulsed lasers that emit laser light. The laser light sources 1a and 1b emit laser light with an output (light intensity) suitable for changing at least one property of the surface or the inside of the container body of the container 6, which is the workpiece. The laser light sources 1a and 1b are capable of controlling the on / off of laser light emission, the emission frequency, the light intensity, etc. As an example of the laser light sources 1a and 1b, a laser light source having a wavelength of 355 nm, a pulse width of the laser light of 10 picoseconds, and an average output of 30 W to 50 W can be used. The diameter of the laser light in the region in the container 6 where the properties of the container body are changed is preferably 1 μm or more and 200 μm or less.

[0024] In the laser marking device according to the first embodiment of Figures 1A and 1B, the case where there are two laser light sources is shown, but it may be configured with three or more laser light sources. When multiple laser light sources are used, it is possible to independently control the on / off, emission frequency, and light intensity of each laser light source. In particular, since the risk of damage to optical components increases when multiple beam spots overlap, it is preferable to independently control the emission frequency and light intensity and shift the output timing of each laser.

[0025] The parallel laser beams emitted from the laser light sources 1a and 1b have their diameters expanded by the beam expanders 2a and 2b, and are incident on the mirror 3a. The mirrors 3a and 3b have a function of changing the reflection angle by a driving unit such as a motor. By changing the reflection angle of the mirrors 3a and 3b, the incident laser light is scanned in the Y direction. For example, a galvanometer mirror, a polygon mirror, or a MEMS (Micro Electro Mechanical System) mirror can be used as the mirrors 3a and 3b.

[0026] The laser marking device of the first embodiment shows an example in which the mirrors 3a and 3b perform one-dimensional scanning of the laser light in the Y direction, but is not limited to this. The mirrors 3a and 3b may be scanning mirrors that change the reflection angle in two orthogonal directions to perform two-dimensional scanning of the laser light in the X and Y directions. However, when irradiating the surface of the cylindrical container 6 with laser light, two-dimensional scanning in the XY directions causes the beam spot diameter on the surface of the container 6 to change in response to scanning in the X direction, so one-dimensional scanning is preferable in such cases.

[0027] The laser light scanned by the mirrors 3a and 3b is irradiated as a processing laser beam 11 onto at least one of the surface and the interior of the container body of the container 6. The lens 5 is a lens that keeps constant the scanning speed of the processing laser beams 11a and 11b scanned by the mirror 3, and converges the processing laser beams 11a and 11b to a predetermined position on at least one of the surface and the interior of the container body of the container 6. As the lens 5, an fθ lens, an arcsine lens, or the like that keeps the scanning speed constant can be used. It is preferable that the lens 5 and the container 6 are arranged so that the beam spot diameter of the processing laser beams 11a and 11b is minimized in the region where the property of the container body of the container 6 is changed. The lens 5 may be composed of a combination of multiple lenses. The synchronous detectors 8a and 8b output synchronous detection signals used to synchronize the scanning angles of the processing laser beams 11a and 11b with the laser output. The synchronous detectors 8a and 8b are provided with photodiodes that output electrical signals according to the intensity of the received light, and output the electrical signals from the photodiodes as synchronous detection signals to the controllers of the laser beams 1a and 1b.

[0028] The container transport unit 21 includes a container 6 transported in the direction of the arrow A, a container detection light source 9 located in front of the scanning position as viewed from the light source, and a container detection sensor 10 located behind the scanning position as viewed from the light source. Although an example of a transmission type sensor is illustrated in the first embodiment of Figs. 1A and 1B, a reflection type sensor may also be used. Since the distance between the sensor position and the scanning position is a known parameter, the writing start timing can be determined from the transport speed and the distance between the sensor position and the scanning position.

[0029] In the laser marking device 100 according to the first embodiment of Figures 1A and 1B, when multiple lasers are used to print using the same scanning means, multiple areas can be drawn simultaneously, thereby improving productivity and saving space. However, the optical components may be damaged by multiple lasers being incident on them. For this reason, it is necessary to shift the positions of multiple laser spots on the optical components as shown in Fig. 2 and Figs. 3A to 3C. However, if the amount of shift in the position of the laser spot is too large, it will go out of the effective range of the optical components, and the amount of light will decrease. In particular, since the optical effective range of the scanning means is limited in size, it is necessary to shift the position of the laser spot to prevent damage, while suppressing the amount of shift of the laser spot position to a range that does not go out of the optical effective range of the scanning means.

[0030] When using a laser with the same output wattage, the smaller the beam diameter incident on the optical components, the higher the energy density, and the greater the risk of damaging the optical components (when the beam diameter is halved, the energy density is four times higher). When the laser's incident diameter is 1.5 mm (50 W, 100 kHz, 10 ps), the energy density is approximately 28 mJ / cm 2 It becomes. In comparison, the damage threshold for optical components compatible with high-power lasers is 0.110 mJ / cm 2 ~10mJ / cm 2 For this reason, from the viewpoint of laser damage resistance, if the incident beam diameter on an optical component is made 1.5 mm or less, the energy density will be more than twice the damage threshold of the optical component, increasing the risk of damaging the optical component, so the incident beam diameter on an optical component is required to exceed 1.5 mm.

[0031] The defocus characteristic of a Gaussian beam depends on the beam diameter incident on the scanning lens, and the larger the incident beam diameter, the smaller the depth margin (deviation of beam diameter relative to defocus). For example, if the workpiece is a plastic bottle, it is expected that the drawing position will vary by about ±2 mm in the defocus direction due to shape errors of the plastic bottle and errors in the transport position. For example, the beam diameter w when the beam waist position x=0 at a wavelength of 355 nm is shown in Figure 3A. In contrast, the deviation in beam diameter due to defocus is shown in Figure 3B. Since the change in beam diameter due to defocus directly affects the drawing quality, it is preferable to keep it to 1 / 5 or less of the required pixel density, and more preferably 1 / 10 or less.

[0032] The pixel density required for prints on PET bottles is generally about 200 dpi to 600 dpi, so the size per dot is 42 μm to 127 μm, and the beam diameter deviation is preferably 8 μm to 25 μm, more preferably 4 μm to 13 μm. In this case, as shown in FIG. 3B, the beam diameter on the image plane is required to be at least Φ30 μm or more. Furthermore, to achieve a beam diameter of 30 μm or more on the image plane, the combination of the focal length of the scanning lens and the beam diameter incident on the scanning lens is as shown in Figure 3C. Since the focal length of the scanning lens contributes to the size of the device, it is preferable that it is f1000 mm or less. Therefore, in order to achieve f1000 mm or less and a beam diameter on the image plane w0' = 30 μm or more, the beam diameter incident on the scanning lens needs to be a maximum of w0 = 17.5 mm or less.

[0033] Generally, lenses have a higher light absorption rate than mirrors, so the risk of damage caused by lasers is higher for lenses. For this reason, it is required that multiple beams do not overlap on the scanning means. Generally, due to size restrictions on the scanning means, the optical paths of multiple lasers are brought closer together in the scanning means to suppress vignetting caused by light beams deviating from the scanning means. For this reason, the first surface of the scanning lens, which is closest to the scanning means, has the optical paths of multiple lasers closest to it, and therefore has the highest risk of damage due to overlapping beam spots from multiple lasers.

[0034] Here, the focal length range assumed for the laser marking device of the first embodiment will be described. In the laser marking device of the first embodiment, a plastic bottle is assumed as a workpiece, and the laser marking device is assumed to be installed in a food manufacturer's factory. Due to space restrictions in a factory, there is a high demand for a compact laser marking device. In particular, since the laser marking device of the first embodiment assumes a high-power laser, the length of the laser alone is 1,000 mm to 2,000 mm, so in order to compact the entire laser marking device, it is required to compact the optical system. Optically, the longer the focal length of the scanning lens is, the longer the working distance becomes, which leads to a larger laser marking device, so the focal length needs to be shortened. However, if the focal length is shortened, the scanning speed on the image plane decreases, which causes a problem of reduced productivity. Therefore, from the viewpoint of the constraints and productivity of the laser marking device, it is preferable that the focal length of the scanning lens is in the range of 100 mm to 1,000 mm.

[0035] In the case of the above focal length, the length L from the scanning means of the scanning lens to the first surface of the scanning lens is 15 mm to 85 mm due to the constraints of the optical performance and external size required of the scanning lens. In order to prevent multiple lasers from overlapping on the scanning lens, the following formula must be satisfied.

[0036]

number

[0037] Therefore, from the above-mentioned beam radii: b1, b2 = 0.75 to 8.5 mm (beam diameter: 1.5 to 17.5 mm) and L = 15 to 85 mm, it is preferable that the intersection half angle θ1 [deg] of the optical paths of multiple lasers satisfies the following equation, 0.5 deg < θ1 < 29.5 deg, because this prevents the beam spots incident on the scanning lens from overlapping, thereby preventing damage to the scanning lens.

[0038] As shown in FIG. 5A, if we assume that the laser intensity distribution can be approximated by a Gaussian distribution, the total input energy can be expressed by the following formula.

[0039]

number

[0040] If the energy input within the effective range r of the optical element in the scanning means is W', it is expressed by the following formula.

number

[0041] The ratio of the energy input during the effective range r of the optical element in the scanning means to the input energy is expressed by the following formula.

number

[0042] When W' / W0=0.95 (efficiency of 95% or more), the effective radius r relative to the laser spot radius b is r>1.22. In reality, this includes the amount of shift from the center of the scanning means (Fig. 5B). Therefore, in order to use an effective range r of the optical element of the scanning means with an efficiency of 95% or more, it is preferable to satisfy the following formula, r>1.22(b+x), in order to suppress the reduction in the amount of light on the optical element of the scanning means. Here, x is the amount of shift of the laser spot from the center of the optical element of the scanning means.

[0043] In order to suppress the reduction in the amount of light on the image plane, it is preferable that W' / W0 = 0.99 (efficiency 99% or more). In this case, the effective range r of the optical element in the scanning means with respect to the laser spot radius b is r > 1.52. In reality, this includes the amount of shift from the center of the scanning means (Fig. 5B). Therefore, in order to use the effective range r of the optical element in the scanning means with an efficiency of 99% or more, it is preferable to satisfy the following formula: r>1.52(b+x), where x is the amount of shift of the laser spot from the center of the optical element in the scanning means.

[0044] In the laser marking device according to the first embodiment, if the required energy density of the workpiece is not reached due to a decrease in the amount of light on the image plane, processing becomes impossible. For this reason, the efficiency in the scanning means is preferably 95% or more, and more preferably 99% or more.

[0045] Here, FIG. 6 is a diagram for explaining the relationship between the beam radius and the effective radius with respect to the amount of displacement of the beam spot on the scanning means. According to this FIG. 6, it can be seen that in order to achieve an efficiency of 95%, it is necessary to set a larger effective radius r than the straight line of efficiency 95% (y = 1.22x). Further, as described above, since a higher efficiency is more advantageous for improving productivity, it is preferable to set a larger effective radius r in the range above the straight line of efficiency 99% (y = 1.52x). Note that the hatched portion A in FIG. 6 is a range that satisfies the following equation: 1.22(b + x) < r.

[0046] FIG. 7 is a diagram for explaining the energy distribution state when two beams are integrated. According to this FIG. 7, since the beam splits into two at around φ / x ≒ 3.5, even if φ / x is made 3.5 or less, the energy density reduction effect disappears. Note that when using two beams and making φ / x 3.5 or less, it becomes equal to the maximum value of the intensity distribution per beam.

[0047] FIGS. 8A and 8B are diagrams for explaining the relationship between the output timing of two lasers and the integrated energy. As shown in FIG. 8A, when the output timings of two lasers are aligned, the maximum energy applied to the optical component becomes E1 + E2, and there is a possibility of damaging the optical component. On the other hand, as shown in FIG. 8B, when the output timings of two lasers are misaligned, the maximum energy applied to the optical component becomes the maximum value of E1 or E2, and the risk of damaging the optical component can be reduced. Here, the case of two lasers is shown for simplicity of explanation, but the same applies when using three or more lasers.

[0048] 9 is a diagram for explaining the relationship between the intersection angle of two lasers and the maximum swing angle of the scanning means. As shown in FIG. 9, in order to eliminate gaps in the drawing range by multiple lasers, the following equation, θ1<θ SCAN (or θ2<θ SCAN ) is preferably satisfied. In the formula, θ1 (or θ2) is the half angle of the intersection of the optical paths of multiple lasers, θ SCAN is the maximum half angle of the scanning means.

[0049] 10A and 10B are diagrams for explaining the configuration of the drawing area in the container. The laser marking device 100 of the first embodiment in Figure 1A shows a case in which the drawing area is divided horizontally relative to the movement control direction A of the container 6, which is the workpiece, and the two-part configuration of the drawing area (red and blue) corresponds to Figure 10A. The laser marking device 100 of the first embodiment in Figure 1B shows a case in which the drawing area is divided vertically relative to the movement control direction A of the container 6, which is the workpiece, and the two-part configuration of the drawing area (red and blue) corresponds to Figure 10B. 1A to 1B and 10A to 10B, for the sake of simplicity, two beams are shown, but three or more beams may be used. The more the beam is divided, the smaller the drawing area per beam becomes, which improves productivity.

[0050] <Modification of the first embodiment of the laser marking device> 11A is a schematic diagram showing an example of a laser marking device 101 according to a modified example of the first embodiment. Note that in the modified example of the first embodiment, the same components as those in the first embodiment already described are given the same reference numerals, and the description thereof will be omitted. Fig. 11B is a diagram showing the direction of light as viewed from direction A in Fig. 11A. Fig. 11C is a diagram showing the spots on galvanometer mirror (GM) 1 in Fig. 11A. Fig. 11D is a diagram showing the spots on galvanometer mirror (GM) 2 in Fig. 11A.

[0051] In the first embodiment of Fig. 1A and Fig. 1B, for the sake of simplicity, an example is shown in which the optical paths intersect on a two-dimensional plane, but in the modified example of the first embodiment shown in Fig. 11A, the optical paths do not intersect when viewed three-dimensionally, but the definition of "intersection of optical paths" also includes the case of Fig. 11A. However, in the case of Fig. 11A, since the distance between the two optical paths is far, if the entrance pupil diameter of the scanning lens after the scanning means is smaller than the distance between the two optical paths and the beam spot diameter, light vignetting occurs in the imaging lens, reducing the amount of light on the image plane. For this reason, it is preferable to have a configuration in which the two optical paths intersect and the entrance pupil of the scanning lens is located at the intersection.

[0052] <Second embodiment of laser marking device> 12A and 12B are schematic diagrams showing a laser marking device 102 according to a second embodiment having three beams from three laser light sources 1a to 1c. Note that in the second embodiment, the same components as those in the first embodiment already described are given the same reference numerals and the description thereof will be omitted. FIG. 12A shows a case where the drawing area is divided horizontally with respect to the movement control direction A of the container 6 which is the workpiece, and the three-division configuration of the drawing area (red, green, and blue) corresponds to FIG. 12C. On the other hand, Figure 12B shows a case where the drawing area is divided vertically to the movement control direction A of the container 6, which is the workpiece, and the three-division configuration of the drawing area (red, green, and blue) corresponds to Figure 12D. According to the second embodiment, the drawing area per beam is reduced compared to the first embodiment, and therefore productivity can be improved.

[0053] <Third embodiment of the laser marking device> 13A and 13B are schematic diagrams showing a laser marking device 103 according to a third embodiment having four beams from four laser light sources 1a to 1d. Note that in the third embodiment, the same components as those in the first embodiment already described are given the same reference numerals and the description thereof will be omitted. This third embodiment uses four laser light sources, which are divided into four in the same direction. Figure 13A shows a case where the drawing area is divided horizontally relative to the movement control direction A of the container 6, which is the workpiece, and the four-part configuration of the drawing area (green, red, blue, and orange) corresponds to Figure 13C. On the other hand, Figure 13B shows a case where the drawing area is divided vertically relative to the movement control direction A of the container 6, which is the workpiece, and the four-part configuration of the drawing area (green, red, blue, and orange) corresponds to Figure 13D. According to the third embodiment, the drawing area per beam is reduced compared to the first embodiment, and therefore productivity can be improved.

[0054] <Modification of the third embodiment of the laser marking device> Fig. 14A is a schematic diagram showing a laser marking device 104 according to a modified example of the third embodiment shown in Fig. 13A and Fig. 13B. Note that in the modified example of the third embodiment, the same components as those in the first embodiment already described are given the same reference numerals, and the description thereof will be omitted. This modified example of the third embodiment uses four laser light sources, which are divided into 2×2 in the main scanning direction and the sub-scanning direction. FIG. 14A shows a case where the image area is divided into two each in the horizontal and vertical directions with respect to the movement control direction A of the container 6 which is the workpiece, and the divided configuration of the image area corresponds to that of FIG. 14B. According to the modified example of the third embodiment, the drawing area per beam is reduced compared to the first embodiment, and therefore productivity can be improved.

[0055] (Container) The container of the present invention is a container manufactured using the laser marking device of the present invention, and has a container body and a visible area in the container body, an image is formed in the container body by the visible area, and the visible area is formed by a collection of patterns.

[0056] <Container body> The container body is not particularly limited in terms of material, shape, size, structure, color, etc., and can be appropriately selected depending on the purpose. The material of the container body is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include resin, glass, etc. Among these, transparent resin or transparent glass is more preferable, and transparent resin is particularly preferable. Examples of resins for the container body include polyvinyl alcohol (PVA), polybutylene adipate or terephthalate (PBAT), polyethylene terephthalate succinate, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), polyurethane, epoxy, biopolybutylene succinate (PBS), polylactic acid blend (PBAT), starch blend polyester resin, polybutylene terephthalate succinate, polylactic acid (PLA), polyhydroxybutyrate / hydroxyhexanoate (PHBH), polyhydroxyalkanoic acid (PHA), bioPET30, biopolyamide (PA) 610, 410, 510, bioPA1012, 10T, bioPA11T, MXD10, biopolycarbonate, biopolyurethane, bioPE, bioPET100, bioPA11, bioPA1010, and the like. These may be used alone or in combination of two or more. Among these, biodegradable resins such as polyvinyl alcohol, polybutylene adipate / terephthalate, and polyethylene terephthalate succinate are preferred from the viewpoint of environmental load.

[0057] The shape of the container body is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a bottle shape, a cylindrical shape, a square prism shape, a box shape, a cone shape, etc. Among these, the bottle shape is preferable. The bottle-shaped container body has a mouth, a shoulder connected to the mouth, a body connected to the shoulder, and a bottom connected to the body. The size of the container body is not particularly limited and can be appropriately selected depending on the application of the container. The structure of the container body is not particularly limited and can be appropriately selected depending on the purpose. For example, it may be a single-layer structure or a multi-layer structure. The color of the container body may be, for example, colorless transparent, colored transparent, colored opaque, or the like.

[0058] <Visible area> The visible area allows an image to be visibly formed on the container body. The image includes, for example, letters, symbols, figures, pictures, codes, etc., and specifically means information such as the name, ingredients, identification number, manufacturer name, manufacturing date and time, expiration date, barcode, QR code (registered trademark), recycle mark, or logo mark. The wavelength of the laser for writing the image is preferably from ultraviolet to near infrared light (wavelength: 300 nm to 2,500 nm). The visible area is formed by a collection of patterns, where the collection means a collection of multiple elements. The assembly of patterns preferably has a structure including recesses formed by melting the container body, or recesses and protrusions continuous with the recesses.

[0059] (Containment Unit) The container of the present invention comprises the container of the present invention and an object contained in the container, and preferably has a sealing means. According to the container of the present invention, the content of the image can be recognized in association with the content of the contained item.

[0060] <Contained Object> Examples of the contained object include liquid, gas, granular solid, etc. Examples of the liquid include water, tea, coffee, black tea, soft drinks, etc. When the contained object is a liquid beverage, it often has a color such as transparent, white, black, brown, or yellow.

[0061] <Sealing means> The sealing means is a means for sealing the contents within the container, and is sometimes called the "container cap." The sealing means is not particularly limited with respect to its material, shape, size, structure, color, etc., and can be appropriately selected depending on the purpose.

[0062] The material of the sealing means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include resin, glass, metal, ceramics, etc. Among these, resin is preferred from the viewpoint of moldability. The resin for the sealing means may be the same as that for the body of the container. The color of the sealing means may be, for example, colored opaque, colored transparent, or the like. The shape and size of the sealing means are not particularly limited as long as they are capable of sealing (closing) the opening of the container body, and can be appropriately selected depending on the purpose.

[0063] Here, embodiments of the container and the pattern in the container of the present invention will be described in detail with reference to the drawings.

[0064] Figures 15A and 15B are scanning electron microscope (SEM) photographs of dot portions 110 in a fine structure as a pattern, with Figure 15A being a perspective view seen from above, and Figure 15B being a perspective view seen from the cross-sectional direction of the arrow DD in Figure 15A. In Figure 15A, two of the multiple dot portions 110 are entirely observed, and also, portions of two dot portions 110 are slightly observed on the positive Y-axis side, and portions of two dot portions 110 are slightly observed on the negative Y-axis side. Also, the dot width is formed to be about 100 μm.

[0065] 15A, the dot portion 110 includes a recess 111 and a protrusion 112. The recess 111 includes a first inclined surface 1111 (hatched portion) and a bottom 1112 (solid black portion), and is formed in a bowl shape. The recess width Dc represents the width of the recess 111, and the depth dp represents the height (length in the Z-axis direction) of the bottom 1112 relative to the surface of the non-pattern region 12.

[0066] Moreover, the protrusion 112 includes an apex 1121 (vertical line hatching portion) and a second inclined surface 1122 (matte hatching portion), and is formed in a torus shape. Note that a torus is a surface of revolution obtained by rotating a circumference. The annular width Dr represents the radial width of the annular surface portion of the protrusion 112, and the height h represents the height of the apex 1121 relative to the surface of the non-pattern region (length in the Z-axis direction).

[0067] The dot width W represents the width of the entire dot portion 110. The first inclined surface 1111 and the second inclined surface 1122 are continuous surfaces. A continuous surface means a surface that is made of the same material and is connected without any steps.

[0068] 15A and 15B, minute unevenness 113 is formed on the surfaces constituting each of the recessed portion 111 and the protruding portion 112, making the surface rough. The unevenness 113 is an example of an unevenness consisting of recessed and protruding portions smaller than a predetermined shape. The unevenness 113 consists of recessed and protruding portions with a width smaller than the dot width W of the dot portion 110, and typically consists of recessed and protruding portions with a width of about 1 μm to 10 μm.

[0069] 15A, chips produced when processing the dot portions 110 are scattered in the regions between the dot portions 110, which also roughens the surface. In the patterned region 13, the surface roughness is greater than that in the non-patterned region due to the surface roughness caused by the uneven portions 113 and chips produced when processing the dot portions 110.

[0070] The dots 110 can be formed, for example, by irradiating the container body 7 with a laser beam to modify the surface of the container body 7. One dot 110 is formed by focusing the laser beam at one point on the container body 7. In addition, a plurality of dots 110 are formed by two-dimensionally scanning the laser beam. Alternatively, the dots 110 can be formed by a plurality of lasers emitted from a plurality of arrayed laser light sources. Furthermore, a mask member having a plurality of light-transmitting openings corresponding to the positions of the dots 110 can be irradiated with an enlarged laser beam, and a plurality of dots 110 can be formed in parallel by a single exposure by each of a plurality of transmitted laser beams that have passed through each light-transmitting opening of the mask member.

[0071] FIGS. 16(a) to (d) show another specific embodiment of the pattern. Fig. 16(a) shows a recess shape formed by evaporating the container body 7 of the container, and Fig. 16(b) shows a recess shape formed by melting the container body 7 of the container. In the case of Fig. 16(b), the periphery of the recess is raised compared to Fig. 16(a). FIG. 16(c) shows the change in the crystallization state on the surface of the container body 7 of the container, and FIG. 16(d) shows the change in the foaming state below the surface of the container body 7 of the container.

[0072] By changing the shape of the surface of the container body of the container, or by changing the properties such as the crystallization state of the surface of the container body or the foaming state below the surface of the container body, a pattern composed of a collection of dots can be formed on the surface of the container body. As a method for forming a recessed shape by evaporating the surface of the container body, for example, a pulsed laser having a wavelength of 355 nm to 1064 nm and a pulse width of 10 fs to 500 nm or less is irradiated, whereby the surface of the container body in the area irradiated with the laser beam is evaporated, and minute recessed portions are formed on the surface. It is also possible to form recesses by melting the surface of the container body by irradiating it with a CW (Continuous Wave) laser with a wavelength of 355 nm to 1064 nm. Furthermore, if the laser continues to be irradiated even after the surface of the container body has melted, the surface or subsurface of the container body can be foamed and become cloudy.

[0073] To change the crystallized state, for example, the container body is made of polyethylene terephthalate (PET), and a CW laser with a wavelength of 355 nm to 1064 nm is irradiated to rapidly raise the temperature of the container body, and then the PET of the container body can be brought into a crystallized state and made opaque by gradually cooling it by reducing the power, etc. After the temperature is raised, if the PET is rapidly cooled by turning off the laser beam, etc., it becomes amorphous and transparent.

[0074] The change in the properties of the container body of the container is not limited to those shown in (a) to (d) of Fig. 16. The properties of the container body may be changed by yellowing, oxidation reaction, surface modification, etc. of the container body made of a resin material. In addition, an absorbent (conversion material) that absorbs the irradiated laser light and converts the light energy into thermal energy can be applied to the container body in advance, and heating control can be performed to form recesses or protrusions in the container body using the thermal energy converted by the absorbent.

[0075] In the above patterns, tiny dots are formed as denatured marks by laser irradiation, and the spacing between these dots is changed to change the density, or the dot shape is changed to a size smaller than can be perceived. The pattern is shown as a tiny, roughly circular shape, but this is not limited to this. It can be an ellipse, an oval, or a line. The shape of the pattern itself can be any shape as long as it is difficult to recognize with the naked eye. It can also be a collection of very thin lines with a very small width.

[0076] For example, aspects of the present invention are as follows. <1> A laser marking device that uses the same scanning means and lens to scan and process the surface of an object with a plurality of lasers, wherein the scanning means includes a first scanning means that scans in a first direction and a second scanning means that scans in a direction substantially orthogonal to the first direction, and the laser marking device is characterized in that the first scanning means is located in an optical path in which the optical paths of the plurality of lasers converge. <2> The laser marking device according to <1>, wherein an intersection position of the optical paths by the plurality of lasers is between the first scanning means and the second scanning means. <3> The laser marking device according to any one of <1> to <2>, wherein a half angle θ1 [deg] of an intersection angle of the optical paths by the plurality of lasers satisfies the following formula: 0.5 deg < θ1 < 29.5 deg. <4> The laser marking device according to any one of <1> to <3>, which satisfies the following formula: 1.22(b + x) < r. However, in the above formula, r represents an effective range of an optical element in the scanning means, b represents a laser spot radius, and x represents a shift amount of the laser spot from the center of the optical element in the scanning means. <5> The laser marking device according to any one of <1> to <4>, wherein the object is controlled to move in the same direction as any of the scanning means. <6> The laser marking device according to any one of <1> to <5>, wherein the plurality of lasers can be controlled to output in time, and the output timing of each laser is controlled to be shifted. <7> The laser marking device according to any one of <1> to <6>, which satisfies the following formula: θ1 < θ scan . However, in the above formula, θ1 represents a half angle of an intersection angle of the optical paths by the plurality of lasers, and θ scan represents a half angle of a maximum swing angle by the scanning means. <8> A configuration for printing on an object that is controlled to move in the same direction as any of the scanning means, The optical paths of the plurality of lasers intersect in a direction that divides the optical paths in a direction substantially perpendicular to the direction in which the lasers are moved. <1> from <7> The laser marking device according to any one of the above items. <9> The above <1> from <8> A container manufactured by the laser marking device according to any one of claims 1 to 5, A container body and a visible area on the container body, The visible area forms an image on the container body, The container is characterized in that the visible area is formed by a collection of patterns. <10> The above <9> A container according to the present invention; and an object to be contained in the container.

[0077] The above <1> from <8> The laser marking device according to any one of the preceding claims. <9> The container according to <10> According to the container described above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0078] 1a Laser light source 1b Laser light source 1c Laser light source 1d Laser Light Source 2a Beam Expander 2b Beam Expander 2c Beam Expander 2d Beam Expander 3a Mirror 3b Mirror 5 Lenses 6 Container 7 Container body 8a Synchronous detection unit 8b Synchronous detection section 9. Light source for container detection 10 Container detection sensor 11a Processing laser beam 11b Processing laser beam 11c Processing laser beam 11d Processing laser beam 13 Pattern Area 20 Laser light source unit to scanning optical system unit 21 Container conveying section 100 Laser marking equipment 101 Laser marking device 102 Laser marking device 103 Laser marking equipment 104 Laser marking device [Prior art documents] [Patent documents]

[0079] [Patent Document 1] Japanese Patent Application Publication No. 11-156567

Claims

1. A laser marking device in which a plurality of lasers scan and process an object surface using the same scanning means and lens, a first scanning means for causing the scanning means to scan in a first direction; A second scanning means for scanning in a direction substantially perpendicular to the first direction; having the first scanning means is located in an optical path where the optical paths of the plurality of lasers converge; The laser marking device is configured so that the output of the multiple lasers can be controlled in time, and is characterized in that the output timing of each laser is controlled to be staggered.

2. 2. The laser marking device according to claim 1, wherein an intersection position of the optical paths of the plurality of lasers is between the first scanning means and the second scanning means.

3. The crossing angle half angle θ of the optical paths of the multiple lasers １ [deg] is the following formula, 0.5 deg < θ １ The laser marking device according to claim 1 , wherein the following condition is satisfied: < 29.5 deg.

4. 4. The laser marking device according to claim 1, wherein the following formula is satisfied: 1.22(b+x)<r. In the above formula, r represents the effective range of the optical element in the scanning means, b represents the radius of the laser spot, and x represents the shift amount of the laser spot from the center of the optical element in the scanning means.

5. 5. The laser marking device according to claim 1, wherein the object is controlled to move in the same direction as any one of said scanning means.

6. The following equation, θ １ <θ ｓｃａｎ 6. The laser marking device according to claim 1, wherein the above-mentioned condition is satisfied. In the above formula, θ １ is the half angle of intersection of the optical paths of multiple lasers, θ ｓｃａｎ and represent the maximum swing angle half angle of the scanning means.

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