JP7589111B2 - Laser Marking System - Google Patents

Description

The present invention relates to a laser marking system that processes an object using a laser beam.

There is an increasing need for laser marking systems that can print information such as expiration dates and manufacturing numbers directly onto objects. Compared to inkjet printing, laser marking can print directly onto the surface of an object, so it is superior in terms of fineness and indelibility, and does not require the use of ink, which has environmental benefits.

Laser marking has issues with printing speed compared to inkjet, which has been an obstacle to its widespread use. For example, Patent Document 1 describes technology for increasing the speed of laser marking. The document proposes a method for simultaneously printing multiple points using a printing pattern.

ES2192485 (Spain)

When the beam is expanded two-dimensionally as in Patent Document 1, the printing speed is improved in principle, but the beam intensity density of the printing points of the printing pattern decreases. Therefore, compared to a method that does not use a printing pattern, a high-output light source is required that corresponds to the ratio of the increased area of the beam spot.

The present invention was made in consideration of the above problems, and proposes a laser marking system that can achieve the same high speed as a two-dimensional printing pattern while suppressing the output of the beam light source.

The laser marking system of the present invention stretches a laser beam in one dimension and modulates the intensity distribution in the major axis direction of the beam spot of the stretched laser beam.

The laser marking system of the present invention can print at a high speed equivalent to that of a two-dimensional print pattern while suppressing the output of the beam light source.

1 is a configuration diagram of a laser marking system 100 according to a first embodiment. 1A to 1C are schematic diagrams illustrating a process of change in a beam spot. FIG. 1 is a configuration diagram of a laser marking system 100 according to a second embodiment. 1A to 1C are schematic diagrams illustrating a process of change in a beam spot. 11A to 11C are schematic diagrams illustrating a process of processing a two-dimensional pattern onto a printing object 5 in the second embodiment. 10 is a schematic diagram showing the synchronization of a modulation operation by a beam modulation unit 3 and an irradiation position changing operation by a beam irradiation position changing unit 8. FIG. FIG. 11 is a configuration diagram of a laser marking system 100 according to a third embodiment. 13 is a schematic diagram showing the result of adjustment of the position where the beam direction adjustment unit 9 irradiates the two-dimensional pattern. FIG. A specific example of a device constituting the beam modulation unit 3 will be described.

<First embodiment>
1 is a configuration diagram of a laser marking system 100 according to a first embodiment of the present invention. The laser marking system 100 is a system that uses a laser beam to print a character string or the like on a marking object 5. The laser marking system 100 includes a light source 1, a beam shaping unit 2, a beam modulation unit 3, a beam irradiation unit 4, a controller 110, and a GUI (Graphical User Interface) 120.

The light source 1 emits a laser beam 6. The light wavelength is set according to the type of the printing object 5. Examples of wavelength: type relationships include the following: (a) ultraviolet light: white resin, transparent resin, black resin; (b) 1 um band infrared light: black objects, metal, objects containing moisture; (c) 10 um band light: glass, transparent resin, paper; (d) green light: black resin.

The beam shaping unit 2 expands the beam in one direction. Expanding in one direction means, for example, extending the shape of the beam spot in one direction on the XY plane. A beam expanded in one dimension in this way is sometimes called a thin-line beam. The beam shaping unit 2 can be constructed, for example, by combining cylindrical lenses. Furthermore, a correction filter may be used so that the intensity distribution in the longitudinal direction of the beam spot is uniform.

The beam modulation unit 3 modulates the intensity distribution in the longitudinal direction of the thin beam. Specific examples of modulation will be described later. The beam modulation unit 3 can be configured using devices used in microdisplays, such as digital mirror devices and liquid crystal devices. By using a one-dimensional GLV (Grating Light Valve), the intensity distribution can be modulated at high speed (for example, about several GHz).

The beam irradiation unit 4 irradiates a thin beam onto the printing object 5. The beam irradiation unit 4 can be configured, for example, with devices such as mirrors and lenses.

The object to be printed 5 may be moving along the direction 7, for example, by a transport mechanism such as a belt conveyor. In this case, the laser marking system 100 processes a pattern on the moving object to be printed 5.

The controller 110 controls each component of the laser marking system 100 (the light source 1 and the beam modulation unit 3 in FIG. 1, and further the beam irradiation position change unit 8 and the beam direction adjustment unit 9 in the embodiment described below). The GUI 120 is a user interface used to input information such as the printing pattern and the type of the printing object 5 to the controller 110.

Figure 2 is a schematic diagram explaining the process of changing the beam spot. The beam spot 11 of the laser light emitted by the light source 1 is approximately circular. The beam shaping unit 2 expands the beam in one dimension to form a thin beam having a major axis and a minor axis like the beam spot 21. It is desirable that the beam power density is uniform in the major axis direction of the beam spot 21. The beam modulation unit 3 modulates the intensity distribution of the beam, so that an area 31a with strong beam intensity and an area 31b with weak beam intensity are formed in the beam spot 31.

The beam intensity in region 31a is set to an extent that allows a pattern to be processed on the printing object 5. The beam intensity in region 31b is set to an extent that does not process the printing object 5. For example, the beam intensity in region 31b may be 0. However, this is not limited to this, and the configuration of this embodiment 1 is useful to the extent that the amount of alteration of the printing object 5 by the laser in region 31a is greater than the amount of alteration by the laser in region 31b, thereby fulfilling the role of printing processing.

If the expansion rate of the beam spot 11 in a one-dimensional direction is R, the intensity of the beam spot 21 is 1/R times that of the beam spot 11. In contrast, when the beam spot is expanded in a two-dimensional direction as in Patent Document 1, the beam intensity becomes 1/R ^2. Therefore, according to the first embodiment, the decrease in beam intensity caused by expanding the beam spot can be suppressed more than in the past.

Since the printing object 5 moves along direction 7, a two-dimensional pattern can be processed on the printing object 5 by changing the shape pattern of areas 31a and 31b over time. When the minor axis direction of the beam spot 31 and direction 7 are aligned, a rectangular two-dimensional pattern can be processed. When the two directions do not match, a two-dimensional pattern can be processed along the relative angle between the two directions.

<Embodiment 1: Summary>
In the laser marking system 100 according to the first embodiment, the beam shaping unit 2 stretches the laser light 6 in one dimension, and the beam modulation unit 3 modulates the intensity distribution in the major axis direction of the beam spot. This makes it possible to efficiently carry out the marking process using the stretched beam spot 31 while maintaining the beam intensity.

In the laser marking system 100 according to the first embodiment, a region 31a having an intensity sufficient to process the marking object 5 and a region 31b having an intensity sufficient to not process the marking object 5 are formed in the beam spot 31. By having both a region to be processed and a region not to be processed, it is possible to process various shape patterns on the marking object 5. Furthermore, by directing the power of the beam to the region 31a, it is possible to maintain the beam intensity.

When enlarging in two dimensions, if the moving speed of the printing object 5 changes, the overlap of the two printing patterns will change, and for example, the overlapping area may increase and the printing patterns may become unreadable, so it is necessary to precisely control the moving speed of the printing object 5. In contrast, the laser marking system 100 of this embodiment 1 is tolerant of changes in the moving speed of the printing object 5, as the printing pattern only compresses or expands in the moving direction.

<Embodiment 2>
Instead of or in combination with moving the printing object 5, a two-dimensional pixel pattern can be scanned with a beam spot to process a two-dimensional pattern on the printing object 5. In the second embodiment of the present invention, a configuration example thereof will be described.

Figure 3 is a configuration diagram of a laser marking system 100 according to the second embodiment. In addition to the configuration described in the first embodiment, the second embodiment includes a beam irradiation position changing unit 8 between the beam shaping unit 2 and the beam modulation unit 3. The other configurations are the same as those in the first embodiment.

The beam irradiation position change unit 8 can change the irradiation position of the laser beam. For example, the beam irradiation position change unit 8 can be configured by a device such as a galvanometer mirror or a polygon mirror.

Figure 4 is a schematic diagram illustrating the process of changing the beam spot. The beam irradiation position changing unit 8 can change the irradiation position of the beam spot along the minor axis direction of the beam spot 81.

Figure 5 is a schematic diagram illustrating the process of processing a two-dimensional pattern on a print target 5 in this embodiment 2. The beam modulation unit 3 is configured to be able to modulate the beam intensity for each pixel that constitutes the two-dimensional pattern to be processed on the print target 5. Figure 5 shows examples of pixel patterns that respectively constitute a downward-to-right diagonal line pattern and an upward-to-right diagonal line pattern.

The beam modulation unit 3 can be configured, for example, by a microdisplay device. The microdisplay can turn the laser beam on and off for each pixel. It turns on the pixel corresponding to region 31a, and turns off the pixel corresponding to region 31b. While the beam modulation unit 3 switches the pixels on and off, the beam irradiation position change unit 8 moves the beam spot 81 along the minor axis direction, whereby a two-dimensional pattern represented by the pixels on and off is printed on the printing object 5.

The modulation speed of the microdisplay is determined by the speed at which pixels are switched on and off (frame rate). By scanning the beam spot 81 on the microdisplay at a speed equal to or faster than the frame rate, the two-dimensional pattern can be printed on the printing target 5 at a speed equivalent to the speed at which the microdisplay forms the two-dimensional pattern.

Microdisplays typically operate at frame rates of around 10 kHz.

Figure 6 is a schematic diagram showing the synchronization of the modulation operation by the beam modulation unit 3 and the irradiation position change operation by the beam irradiation position change unit 8. Some devices constituting the beam modulation unit 3 are configured to switch the beam intensity of all pixels sequentially according to a switching speed, rather than simultaneously switching (i.e., simultaneously switching ON/OFF of all pixels). For example, a microdisplay is configured to switch each pixel sequentially along the X direction shown in Figure 6. The X direction coincides with the minor axis direction of the beam spot 81. In the example of Figure 6, the beam modulation unit 3 first switches ON/OFF of each pixel in the first column with the smallest X coordinate, then switches ON/OFF of each pixel in the second column, and similarly switches ON/OFF sequentially from the third column onwards.

When the beam modulation unit 3 is configured in this way, it is necessary to irradiate the beam spot 81 in the order of columns for which ON/OFF switching has been completed. In the example of FIG. 6, the beam spot 81 is irradiated in the order of columns, starting from the first column with the smallest X coordinate. In this way, the ON/OFF pattern for each X coordinate is processed on the printing object 5 for each column. When the beam modulation unit 3 has completed ON/OFF switching for the pixel with the last X coordinate, it returns to the initial X coordinate and switches ON/OFF again, starting from the first column.

By synchronizing the operation of the beam modulation unit 3 to switch the pixel ON/OFF pattern with the operation of the beam irradiation position change unit 8 to move the irradiation position of the beam spot 81, it is possible to reduce the waiting time between the two operations. The graph on the right of Figure 6 shows this process.

The operation of the beam modulation unit 3 to switch the ON/OFF pattern of pixels is indicated by the reference symbol 32. The beam modulation unit 3 starts from time t=0 and switches the pixel pattern in sequence starting from the first column. As time progresses, the X coordinate also progresses.

When the beam modulation unit 3 has completed updating the pixel pattern for half the X-direction size of the print pattern, the beam irradiation position change unit 8 begins irradiating the beam modulation unit 3 with the beam spot 81. This operation is indicated by the reference numeral 82. The speed at which the beam modulation unit 3 advances the X-coordinate of the pixel pattern and the speed at which the beam irradiation position change unit 8 moves the X-coordinate of the beam spot 81 are approximately equal. Therefore, the inclinations of the reference numerals 32 and 82 are approximately equal.

When the beam modulation unit 3 has finished updating the pixel pattern for the final X coordinate of the print pattern, it returns to the initial X coordinate. At this point, the beam spot 81 is at a position that is approximately half the X-direction size of the print pattern. Furthermore, when the beam modulation unit 3 has finished updating the pixel pattern for half the X-direction size of the print pattern, the beam irradiation position change unit 8 irradiates the beam spot 81 to the final X coordinate and returns to the initial X coordinate. Subsequent operations are similar.

By performing the above-described synchronous operation, the beam irradiation position changing unit 8 does not need to wait for irradiation until the beam modulation unit 3 has finished updating all pixel patterns, so the waiting time between the two can be minimized.

In FIG. 6, if the operating speed of reference numeral 32 and the operating speed of reference numeral 82 are the same, the speeds of the two can be said to be synchronized, but this is not necessarily the case. For example, even if the speed at which the beam modulation unit 3 updates the pixel pattern is slightly faster, the beam modulation unit 3 can wait until the operation of the beam irradiation position change unit 8 catches up each time it returns to the initial X coordinate. Even in this case, the operations of the two can be said to be synchronized every cycle.

<Embodiment 2: Summary>
In the laser marking system 100 according to the second embodiment, the beam modulation unit 3 is configured to sequentially update the pixel pattern along the minor axis direction (X direction) of the beam spot 81 (switching the beam ON/OFF for each pixel), and the beam irradiation position change unit 8 moves the beam spot 81 along the same direction. This makes it possible to process the two-dimensional pattern formed by the beam modulation unit 3 onto the printing object 5. This function can be realized regardless of whether the printing object 5 moves or not.

The laser marking system 100 according to the second embodiment synchronizes the operation of the beam modulation unit 3 to turn on/off the pixels of the two-dimensional pattern (i.e., the operation to modulate the beam intensity in the beam spot 31) with the operation of the beam irradiation position change unit 8 to irradiate the beam spot 81 onto the beam modulation unit 3. This reduces the waiting time between the two operations, enabling high-speed printing to be achieved.

<Third embodiment>
Fig. 7 is a configuration diagram of a laser marking system 100 according to a third embodiment of the present invention. In this third embodiment, in addition to the configuration described in the first or second embodiment, a beam direction adjustment unit 9 is provided between the beam modulation unit 3 and the beam irradiation unit 4. The other configuration is the same as in the first or second embodiment. Fig. 7 shows an example in which the beam direction adjustment unit 9 is provided in addition to the second embodiment.

The beam direction adjustment unit 9 adjusts the direction in which the beam spot 31, whose intensity distribution has been modulated by the beam modulation unit 3, is projected. Specifically, the position at which the two-dimensional pattern formed by the beam modulation unit 3 is projected onto the printing object 5 is adjusted by directing the beam. This makes it possible to adjust the position at which the two-dimensional pattern is processed on the printing object 5. The beam direction adjustment unit 9 can be configured, for example, by one or more galvanometer mirrors.

Figure 8 is a schematic diagram showing the result of adjusting the position at which the beam direction adjustment unit 9 irradiates the two-dimensional pattern. The size of the two-dimensional pattern formed by the beam modulation unit 3 is limited, for example, pattern 51 in Figure 8. In order to print a pattern larger than the two-dimensional pattern formed by the beam modulation unit 3, it is necessary to scan the irradiation position of the two-dimensional pattern itself. The beam direction adjustment unit 9 achieves this by directing the beam. The left diagram in Figure 8 shows an example where five patterns 51 are arranged in one row x five columns. The right diagram in Figure 8 shows an example where ten patterns 51 are arranged in two rows x five columns. Each pattern does not have to be the same.

At the boundary between patterns 51, overlapping portions 52 may be provided. In portions 52, for example, the average value of the surrounding pixels may be placed, thereby reducing the sense of incongruity in appearance without impairing the continuity of the boundary between patterns. Note that if the printing target 5 moves, it is necessary to monitor the moving speed and control the overlapping area in the moving direction.

<Embodiment 3: Summary>
In the laser marking system 100 according to the third embodiment, the beam direction adjustment unit 9 orients the two-dimensional pattern formed by the beam modulation unit 3, so that a pattern in which a plurality of two-dimensional patterns are arranged side by side can be processed on the printing object 5. This makes it possible to process even two-dimensional patterns larger than the two-dimensional pattern formed by the beam modulation unit 3.

<Fourth embodiment>
Fig. 9 shows specific examples of devices constituting the beam modulation unit 3. The upper part of Fig. 9 shows an example in which a DMD (Digital Micromirror Device) 31 is used as the beam modulation unit 3. The lower part of Fig. 9 shows an example in which a LCOS (Liquid Crystal On Silicon) 32 is used as the beam modulation unit 3. A polygon mirror, for example, can be used as the beam irradiation position changing unit 8.

The DMD 31 has good printing efficiency because it does not require a polarizing filter. The LCOS 32 has the advantage of being able to improve contrast by using a polarizing film 33. However, its light utilization efficiency is lower than that of the DMD. The DMD 31 has the advantage of being more durable against ultraviolet light than the LCOS 32.

<Modifications of the present invention>
The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

In the second embodiment, it has been described that a pixel pattern is printed by turning the laser beam on and off for each pixel. In this case, each pixel can be expressed by one bit. The second embodiment is not limited to this, and for example, it is also possible to print a pixel pattern expressed by multiple bits for each pixel using a laser beam intensity corresponding to the gradation expressed by the multiple bits. In other words, by modulating the beam intensity for each irradiation position (pixel position) of the beam spot, it is possible to print pixel patterns having various gradation patterns.

The controller 10 can be configured by hardware such as a circuit device that implements its functions, or by a computing device such as a CPU (Central Processing Unit) that executes software that implements its functions. The GUI 120 can be configured, for example, by the controller 110 presenting an operation screen on a display device such as a display.

1: Light source 2: Beam shaping section 3: Beam modulation section 4: Beam irradiation section 5: Printing object 8: Beam irradiation position change section 9: Beam direction adjustment section 100: Laser marking system 110: Controller 120: GUI

Claims (13)

A laser marking system for processing an object with a laser beam, comprising:
a light source that emits the laser beam;
A beam shaping unit that stretches the laser beam in one dimension;
a beam modulation unit that modulates an intensity distribution in a major axis direction of a beam spot of the elongated laser beam;
a beam irradiation unit that irradiates the modulated laser beam onto the object;
Equipped with
the laser marking system is configured to process the moving object;
The direction in which the object moves is the minor axis direction of the beam spot.
A laser marking system comprising: A laser marking system for processing an object with a laser beam, comprising:
a light source that emits the laser beam;
A beam shaping unit that stretches the laser beam in one dimension;
a beam modulation unit that modulates an intensity distribution in a major axis direction of a beam spot of the elongated laser beam;
a beam irradiation unit that irradiates the modulated laser beam onto the object;
Equipped with
the beam modulation unit modulates the laser beam so as to form, within the beam spot, a first region having a beam intensity of a first intensity and a second region having a beam intensity of a second intensity smaller than the first intensity;
the beam modulation unit modulates the laser beam to have the first area and the second area at a first time;
the beam modulation unit modulates the laser beam to have a third region having the first intensity and a fourth region having the second intensity at a second time;
The laser marking system further includes a beam irradiation position changing unit that processes a two-dimensional pattern constituted by the first area, the second area, the third area, and the fourth area on the object by moving an irradiation position of the beam spot between the first time and the second time.
A laser marking system comprising: A laser marking system for processing an object with a laser beam, comprising:
a light source that emits the laser beam;
A beam shaping unit that stretches the laser beam in one dimension;
a beam modulation unit that modulates an intensity distribution in a major axis direction of a beam spot of the elongated laser beam;
a beam irradiation unit that irradiates the modulated laser beam onto the object;
Equipped with
The laser marking system further includes a beam direction adjustment unit that adjusts a direction of the laser beam emitted by the beam irradiation unit,
the beam modulation unit is configured to be able to modulate an intensity distribution of the laser beam within the beam spot within a two-dimensional area,
The beam direction adjustment unit processes the object with the laser beam in a region having a planar size larger than the two-dimensional region by directing the laser beam to the region having a planar size larger than the two-dimensional region.
A laser marking system comprising: 4. The laser marking system according to claim 1, wherein the beam modulation unit modulates the laser beam so as to form, within the beam spot, a first region having a beam intensity of a first intensity and a second region having a beam intensity of a second intensity smaller than the first intensity. 5. The laser marking system of claim 4, wherein the beam modulation unit configures the first intensity to have a beam intensity that alters the object by a first amount, and configures the second intensity to have a beam intensity that alters the object by a second amount smaller than the first amount. The laser marking system according to claim 5 , wherein the beam modulating unit sets the second intensity to zero by blocking the laser beam. 3. The laser marking system according to claim 2 , wherein the beam irradiation position changing unit moves the irradiation position of the beam spot in a minor axis direction of the beam spot. The beam modulation unit is configured to be able to modulate the intensity of the laser beam for each two-dimensional pixel region,
The beam modulation unit is configured to sequentially update the intensity of the laser beam in the pixel area along a minor axis direction of the beam spot,
The laser marking system according to claim 2, characterized in that the beam irradiation position changing unit changes the irradiation position of the beam spot so that the beam spot is irradiated in the order of the pixel areas for which the beam modulation unit has updated the intensity of the laser beam . the beam modulation unit sequentially updates the intensity of the laser beam along the minor axis direction in order from a start position of the two-dimensional pattern in the minor axis direction;
the beam irradiation position changing unit starts irradiating the beam spot and moves the beam spot along the short axis direction when the beam modulation unit completes updating the intensity of the laser beam for an area corresponding to half the size of the two-dimensional pattern in the short axis direction;
The laser marking system according to claim 8, characterized in that, when the beam modulation unit finishes updating the intensity of the laser beam for the entire two-dimensional pattern along the short axis direction, the beam modulation unit returns to the starting position and again sequentially updates the intensity of the laser beam along the short axis direction. 10. The laser marking system according to claim 9, wherein the operation of the beam modulation unit to update the intensity of the laser beam and the operation of the beam irradiation position change unit to move the beam spot are synchronized. the beam modulation unit modulates the laser beam at a first time such that an intensity distribution of the laser beam within the beam spot has a first planar pattern;
the beam modulation unit modulates the laser beam at a second time such that an intensity distribution of the laser beam within the beam spot has a second planar pattern;
The laser marking system of claim 3, characterized in that the beam direction adjustment unit irradiates the laser beam of the first planar pattern onto a first area on the object, and irradiates the laser beam of the second planar pattern onto a second area on the object, thereby processing a planar pattern on the object that is a sum of the first planar pattern and the second planar pattern. The laser marking system of claim 11 , characterized in that the first planar pattern processed on the object and the second planar pattern processed on the object partially overlap at their boundary portion. The laser marking system further includes a controller that controls the laser marking system by controlling the light source, the beam shaping unit, and the beam modulation unit;
The laser marking system further includes a user interface for receiving an instruction input indicating a shape pattern to be processed on the object;
The laser marking system according to any one of claims 1 to 3 , wherein the controller controls the laser marking system so as to process the shape pattern received by the user interface on the object.

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