JP7647433B2 - Laser marking equipment - Google Patents

Description

The present invention relates to a laser marking device .

Conventionally, containers such as polyethylene terephthalate (PET) bottles are known to have labels affixed to them indicating the name, ingredients, expiration date, barcodes, and other images. Meanwhile, there has been a recent worldwide movement to eliminate pollution caused by plastic waste, and there is an increasing demand for closed-loop recycling of containers. Here, closed-loop recycling of containers refers to recycling companies turning used containers that have been separated and collected into flakes that can be used to manufacture containers again.

To facilitate this type of circular recycling, it is preferable to thoroughly separate and collect waste by container or label, etc., but the task of removing labels from containers for separate collection is time-consuming and is one of the constraints on thorough separate collection.

In contrast, known methods for processing transparent objects such as transparent resins with laser light include processing using an infrared wavelength of 10.6 μm with a CO ₂ laser or the like, or processing using an ultraviolet wavelength of 355 nm.
In the processing using infrared wavelengths, the beam spot diameter cannot be narrowed sufficiently, so high-resolution drawing is realized by narrowing the beam spot diameter using ultraviolet wavelengths. However, since pulse energy exceeding the processing threshold (average laser output determined by the repetition frequency) 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 repetition frequency of the laser. On the other hand, if the frequency is high, the pulse energy becomes low, so one dot cannot be processed with one pulse, and multiple pulses are required. As a result, the frequency for forming one dot becomes low, which is a problem in that it is difficult to increase productivity.

To solve the above problems, a laser processing device has been proposed that uses the same optical system to scan and focus multiple lasers, thereby dividing the processing area according to the number of lasers installed, thereby increasing processing speed while reducing costs and size. For example, a laser marking device has been proposed in which multiple beams are incident on an fθ lens at different angles using the same two-dimensional scanning means and fθ lens (see, for example, Patent Document 1).

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 in the same optical system.

The laser marking device of the present invention, as a means for solving the above problems, 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, the first scanning means is located in an optical path where the optical paths of the multiple lasers converge , and the multiple lasers are configured to be able to be output controlled in time, and the output timing of each laser is controlled to be staggered .

The present invention provides a laser marking device that can prevent damage to optical components and suppress a decrease in the amount of light in an optical system that scans and focuses multiple laser beams in the same optical system.

FIG. 1A is a schematic diagram showing an example of a laser marking device according to a first embodiment. FIG. 1B is a schematic diagram showing another example of the laser marking device of the first embodiment. FIG. 2 is a diagram for explaining the configuration of light beams produced by a plurality of lasers. 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. 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. FIG. 3C is a graph showing the relationship between the incident beam diameter and the beam diameter on the image plane. FIG. 4 is a diagram for explaining the positional relationship between the effective radius and the beam spot diameter in the scanning means. 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. 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. 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. FIG. 7 is a diagram for explaining the energy distribution state when two beams are integrated. 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. 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. 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. 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. 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. FIG. 11A is a schematic diagram showing an example of a laser marking device according to a modified example of the first embodiment. FIG. 11B is a diagram showing the direction of light rays as viewed from the direction A in FIG. 11A. FIG. 11C shows the spots on GM1 in FIG. 11A. FIG. 11D shows the spots on GM2 in FIG. 11A. FIG. 12A is a schematic diagram showing an example of a laser marking device according to the second embodiment. FIG. 12B is a schematic diagram showing another example of the laser marking device according to the second embodiment. FIG. 12C 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 the horizontal direction relative to the container movement control direction. FIG. 12D 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 a direction perpendicular to the container movement control direction. FIG. 13A is a schematic diagram showing an example of a laser marking device according to the third embodiment. FIG. 13B is a schematic diagram showing another example of the laser marking device according to the third embodiment. FIG. 13C is a diagram for explaining the direction 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. 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. FIG. 14A is a schematic diagram showing an example of a laser marking device according to a modified example of the third embodiment. FIG. 14B is a diagram for explaining directions in which the four lasers are split in the modified third embodiment. FIG. 15A is a scanning electron microscope photograph of a dot portion in a fine structure as a pattern, and is a perspective view viewed from above. 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 indicated by arrows DD in FIG. 15A. FIG. 16 is a schematic diagram showing a specific embodiment of a pattern on a container.

(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.

In the conventional technology of Patent Document 1 (JP Patent Publication No. 11-156567), there is a problem that multiple laser beams overlap on the 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, the beam spot will move out of the effective range of the optical components, reducing the amount of light and making processing impossible. In addition, in Figure 1 of the above-mentioned JP Patent Publication No. 11-156567, the optical paths of multiple beams intersect in front of the scanning means, and the spacing between the optical paths becomes wider as the device approaches the scanning means, which creates a problem that the device as a whole becomes larger as the device moves away from the intersection of the multiple optical paths.

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, damage to the optical elements can be suppressed, and by minimizing the amount of positional deviation from the optical elements, a reduction in the amount of light caused by the beam spot moving out of the effective range of the optical components can be suppressed.

In one aspect of the present invention, the intersection point 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 light intensity due to light vignetting. According to this aspect, 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.

In one aspect of the present invention, it is preferable that the half angle θ ₁ [deg] of the intersection angle of the optical paths of the multiple lasers satisfies the following formula: 0.5 deg<θ ₁ <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.

In one embodiment of the present invention, it is preferable to satisfy the following formula: 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.
According to this aspect, it is possible to suppress a decrease in the amount of light on the optical elements (e.g., galvanometer mirror, polygon mirror) of the scanning means. Note that the coefficient 1.22 in the above formula is for the case where an efficiency of 95% or more is achieved, and the coefficient becomes 1.52 for the case where an efficiency of 99% or more is achieved.

In one aspect of the present invention, the movement of an object is controlled in the same direction as one of the scanning means. According to this aspect, by controlling the movement of an object in the same direction as one of the scanning means, the swing angle of the scanning means can be reduced, improving productivity.

In one aspect of the present invention, multiple lasers can be configured to have their output controlled over time, and damage to optical components can be suppressed by controlling the output timing of each laser to be offset.

In one aspect of the present invention, it is preferable to satisfy the following formula: θ ₁ <θ _scan .
In the above formula, θ ₁ represents the half angle of intersection of the optical paths of the multiple lasers, and θ _scan represents the half angle of the maximum deflection angle of the scanning means.

In one aspect of the present invention, the configuration is such that printing is performed on an object whose movement is controlled in the same direction as one of the scanning means, and the optical paths of multiple lasers intersect in a direction that divides the object in a direction that is approximately perpendicular to the direction of the controlled movement. According to this aspect, by dividing the drawing range in a direction that is approximately perpendicular to the direction of the controlled movement of the object to be printed (main division), the scanning time in the main scanning direction can be shortened, and productivity can be improved.

Here, an embodiment of the laser marking device of the present invention will be described in detail with reference to the drawings. Note that 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 components described below are not limited to this embodiment, and may be any number, position, shape, etc. that is preferable for implementing the present invention.

<First embodiment of 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.

The scanning optical system 20 from the laser light source unit 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 polygon mirrors such as polygon scanners.

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.

In the laser marking device according to the first embodiment of FIG. 1A and FIG. 1B, two laser light sources are shown, but it may be configured with three or more laser light sources. When multiple laser light sources are used, it may be 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 stagger the output timing of each laser.

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. As the mirrors 3a and 3b, for example, a galvanometer mirror, a polygon mirror, a MEMS (Micro Electro Mechanical System) mirror, or the like can be used.

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.

The laser light scanned by the mirrors 3 a and 3 b 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 arc sine 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 properties of the container body of the container 6 are 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 control units of the laser beams 1a and 1b.

The container transport unit 21 includes a container 6 transported in the direction of 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. Note that, although an example of a transmission type sensor is illustrated in the first embodiment of FIG. 1A and FIG. 1B, a reflective type sensor may also be used. Since the distance between the sensor position and the scanning position is a known parameter, the write start timing can be determined from the transport speed and the distance between the sensor position and the scanning position.

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 Figures 2 and 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.

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 has an incident diameter of 1.5 mm (50 W, 100 kHz, 10 ps), the energy density is approximately 28 mJ/ ^cm2 .
In contrast, the damage threshold of optical components compatible with high-power lasers is often on the order of 0.110 mJ/cm ² to 10 mJ/cm ^2. For this reason, from the standpoint of laser damage resistance, if the incident beam diameter on the optical components is set to 1.5 mm or less, the energy density will be more than twice the damage threshold of the optical components, increasing the risk of damaging the optical components, and therefore it is required that the incident beam diameter on the optical components exceeds 1.5 mm.

The defocus characteristic of the 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 the beam diameter relative to the defocus). For example, when 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 the shape error of the plastic bottle and the error of the conveying 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 Fig. 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.

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, in order 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 FIG. 3C. Since the focal length of the scanning lens contributes to the size of the device, it is preferable that f is 1000 mm or less. Therefore, in order to achieve f 1000 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.

Generally, lenses have a higher light absorption rate than mirrors, so the risk of damage from 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 constraints on the scanning means, the optical paths of multiple lasers are brought closer together in the scanning means to suppress vignetting of light rays caused by light rays straying 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 the multiple lasers closest, and therefore has the highest risk of damage due to overlapping beam spots from multiple lasers.

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, the workpiece is assumed to be a plastic bottle, and the laser marking device is assumed to be installed in a food manufacturer's factory. Due to space restrictions in factories, 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, 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 is a problem in that productivity is reduced. 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.

For the above focal length, the length L from the scanning means of the scanning lens to the first surface of the scanning lens is L = 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.

Therefore, from the above-mentioned beam radii: b1, b2 = 0.75 to 8.5 mm (beam diameter: 1.5 to 17.5 mm), L = 15 to 85 mm, it is preferable that the intersection half angle θ ₁ [deg] of the optical paths of the multiple lasers satisfies the following equation, 0.5 deg < θ ₁ < 29.5 deg, since this prevents the beam spots incident on the scanning lens from overlapping, thereby suppressing damage to the scanning lens.

Assuming that the laser intensity distribution can be approximated by a Gaussian distribution, as shown in Figure 5A, the total energy input can be expressed by the following formula.

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.

The ratio of the energy injected into the effective range r of the optical element of the scanning means to the injected energy is expressed by the following formula:

When W'/W ₀ =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 the 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 decrease 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.

In order to suppress a reduction in the amount of light on the image plane, it is preferable that W'/ _W0 = 0.99 (efficiency of 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.

In the laser marking device of the first embodiment, if the amount of light on the image plane decreases and the energy density falls below the required energy density of the workpiece, processing becomes impossible. For this reason, the efficiency of the scanning means is preferably 95% or more, and an efficiency of 99% or more is even more preferable.

Here, FIG. 6 is a diagram for explaining the relationship between the beam radius and the effective radius with respect to the positional deviation of the beam spot on the scanning means. From FIG. 6, it can be seen that in order to achieve an efficiency of 95%, it is necessary to set an effective radius r larger than the line of 95% efficiency (y = 1.22x). As mentioned above, the higher the efficiency, the more advantageous it is for improving productivity, so it is preferable to set a large effective radius r in the range equal to or larger than the line of 99% efficiency (y = 1.52x). Note that the hatched area A in FIG. 6 is the range that satisfies the following formula, 1.22(b + x) < r.

FIG. 7 is a diagram for explaining the energy distribution state when two beams are integrated.
According to Fig. 7, the beam splits into two when φ/x ≈ 3.5, so even if φ/x is set to 3.5 or less, the effect of reducing the energy density disappears. Note that even if two beams are used, when φ/x is set to 3.5 or less, the maximum intensity distribution becomes equivalent to the maximum value per beam.

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 the two lasers are aligned, the maximum energy given to the optical components is E1 + E2, which may damage the optical components. On the other hand, as shown in Fig. 8B, when the output timings of the two lasers are out of sync, the maximum energy given to the optical components is the maximum value of E1 or E2, which reduces the risk of damaging the optical components. Here, the case of two lasers is shown for the sake of simplicity, but the same applies when three or more lasers are used.

Fig. 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 ranges of the multiple lasers, it is preferable to satisfy the following formula, _θ1 < _θSCAN (or _θ2 < _θSCAN ).
In the formula, θ ₁ (or θ ₂ ) is the half angle of intersection of the optical paths of the multiple lasers, and θ _SCAN is the half angle of the maximum deflection angle of the scanning means.

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 where 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, the number of beams is two, but the number of beams may be three or more. The more the beam is divided, the smaller the drawing area per beam becomes, which improves productivity.

<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 the direction A in Fig. 11A. Fig. 11C is a diagram showing the spots on the galvanometer mirror (GM) 1 in Fig. 11A. Fig. 11D is a diagram showing the spots on the galvanometer mirror (GM) 2 in Fig. 11A.

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 large, 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.

<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.
Figure 12A 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 three-part configuration of the drawing area (red, green, and blue) corresponds to Figure 12C.
On the other hand, Figure 12B 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 three-part 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.

<Third embodiment of 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 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 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.

<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 container 6, which is the workpiece, is divided into two in each of the horizontal and vertical directions with respect to the movement control direction A, and the divided configuration of the image region 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.

(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 on the container body, an image is formed on the container body by the visible area, and the visible area is formed by a collection of patterns.

<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), bio-PET30, bio-polyamide (PA) 610, 410, 510, bio-PA1012, 10T, bio-PA11T, MXD10, bio-polycarbonate, bio-polyurethane, bio-PE, bio-PET100, bio-PA11, bio-PA1010, 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.

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 preferred.
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.

<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 pattern assembly preferably has a structure including recesses formed by melting the container body, or recesses and protrusions continuous with the recesses.

(Containment Body)
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.

<Items Detained>
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.

<Sealing means>
The sealing means is a means for sealing the contained object within the container, and is sometimes called a "container cap." There are no particular restrictions on the material, shape, size, structure, color, etc. of the sealing means, and it can be selected appropriately depending on the purpose.

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.

Here, the embodiments of the patterns in the container and container of the present invention will be described in detail with reference to the drawings.

Figures 15A and 15B are scanning electron microscope (SEM) photographs of dot portions 110 in a microstructure 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 arrows D-D 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. The dot width is formed to be approximately 100 μm.

As shown in FIG. 15A, the dot portion 110 is composed of 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.

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

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.

As shown in Figures 15A and 15B, minute irregularities 113 are formed on the surfaces constituting each of the recesses 111 and the protrusions 112, making the surfaces rough. The irregularities 113 are an example of an irregularity consisting of recesses and protrusions smaller than a predetermined shape. The irregularities 113 consist of recesses and protrusions with a width smaller than the dot width W of the dot portion 110, and typically consist of recesses and protrusions with a width of about 1 μm to 10 μm.

As shown in FIG. 15A, chips from the process of machining the dots 110 are scattered in the areas between the dots 110, which also roughens the surface. In the patterned area 13, the surface roughness is greater than in the non-patterned area due to the surface roughness caused by the unevenness 113 and chips from the process.

The dots 110 can be formed, for example, by irradiating the container body 7 with laser light and modifying the surface of the container body 7. One dot 110 is formed by focusing the laser light at one point on the container body 7. In addition, multiple dots 110 are formed by scanning this laser light in two dimensions. Alternatively, they can be formed by multiple lasers emitted from multiple arrayed laser light sources. Furthermore, multiple dots 110 can be formed in parallel with one exposure by irradiating an enlarged laser light onto a mask member having multiple light-transmitting openings corresponding to the positions of each dot 110, and using each of the multiple transmitted laser light groups that pass through each light-transmitting opening of the mask member.

Figures 16(a)-(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.

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 the 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 portion irradiated with the laser beam is evaporated, and minute recessed portions are formed on the surface.
It is also possible to melt the surface of the container body and form a recess 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.

To change the crystallized state, for example, the container body can be made of polyethylene terephthalate (PET), and a CW laser with a wavelength of 355 nm to 1064 nm can be irradiated to rapidly raise the temperature of the container body, and then the power can be gradually reduced to slowly cool the container body, thereby bringing the PET of the container body into a crystallized state and making it opaque. Note that if the PET is rapidly cooled by turning off the laser beam after the temperature has been raised, the PET will become amorphous and transparent.

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.

In the above patterns, tiny dots are formed as denatured marks caused by laser irradiation, and the spacing between these dots can be changed to change the density, or the dot shape can be 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 also be elliptical, oval, or linear. The shape of the pattern itself can be any shape as long as it is difficult to discern with the naked eye. It can also be a collection of very thin lines.

For example, aspects of the present invention are as follows.
<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 scanning the scanning means in a first direction, and a second scanning means for scanning the scanning means in a direction substantially perpendicular to the first direction;
having
The laser marking device is characterized in that the first scanning means is positioned in an optical path where the optical paths of the multiple lasers converge.
<2> The laser marking device according to <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 laser marking device according to any one of <1> and <2>, wherein a half angle θ ₁ [deg] of an intersection angle between the optical paths of the plurality of lasers satisfies the following formula: 0.5 deg<θ ₁ <29.5 deg.
<4> The laser marking device according to any one of <1> to <3>, wherein the following formula: 1.22(b+x)<r is satisfied.
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> The laser marking device according to any one of <1> to <4>, wherein the movement of the object is controlled in the same direction as any one of the scanning means.
<6> The laser marking device according to any one of <1> to <5>, wherein the output of the plurality of lasers can be controlled in time, and the output timing of each laser is controlled to be staggered.
<7> The laser marking device according to any one of <1> to <6>, wherein the following formula, θ ₁ <θ _scan , is satisfied.
In the above formula, θ ₁ represents the half angle of intersection of the optical paths of the multiple lasers, and θ _scan represents the half angle of the maximum deflection angle of the scanning means.
<8> A configuration for printing on an object that is controlled to move in the same direction as any one of the scanning means,
The laser marking device according to any one of <1> to <7>, wherein the optical paths of the multiple lasers intersect in a direction that splits the laser beam in a direction that is approximately perpendicular to the direction in which the laser beam is moved.
<9> A container manufactured by the laser marking device according to any one of <1> to <8>,
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 container according to <9>,
and an object to be contained in the container.

The laser marking device described in any one of <1> to <8>, the container described in <9>, and the container described in <10> can solve the problems of the past and achieve the object of the present invention.

Description of the Reference Numerals 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 Lens 6 Container 7 Container body 8a Synchronization detection unit 8b Synchronization detection unit 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 From laser light source unit to scanning optical system unit 21 Container conveying unit 100 Laser marking device 101 Laser marking device 102 Laser marking device 103 Laser marking device 104 Laser marking device

Japanese Patent Application Publication No. 11-156567

Claims (6)

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 . The laser marking device according to claim 1, wherein the intersection position of the optical paths of the multiple lasers is between the first scanning means and the second scanning means. 3. The laser marking device according to claim 1, wherein a half angle θ ₁ [deg] of intersection angle of optical paths of the plurality of lasers satisfies the following formula: 0.5 deg<θ ₁ <29.5 deg. 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. A laser marking device according to any one of claims 1 to 4, in which the movement of an object is controlled in the same direction as any one of the scanning means. 6. The laser marking device according to claim 1, which satisfies the following formula: θ ₁ <θ _scan .
In the above formula, θ ₁ represents the half angle of intersection of the optical paths of the multiple lasers, and θ _scan represents the half angle of the maximum deflection angle of the scanning means.