Laser irradiation apparatus and laser irradiation method

Abstract

To adjust irradiation time of each laser irradiation portion.SOLUTION: A laser irradiation apparatus 1 includes a plurality of laser irradiation portions 100A and 100B for irradiating laser light, where the plurality of laser irradiation portions 100A and 100B respectively irradiate the same container 50 with laser light of a plurality of irradiating contents having different irradiating times, and the irradiating contents irradiated by the laser irradiation portions 100A and 100B are switched in a process of irradiating the plurality of containers 50 with the laser light.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a laser irradiation device and a laser irradiation method. [Background technology]

[0002] Some laser irradiation devices use a plurality of laser irradiation units each having a laser oscillation source to sequentially irradiate an object to be irradiated as it is conveyed along a line with laser light, thereby forming a desired image on the object to be irradiated.

[0003] In such a laser irradiation device, the amount of laser light emitted from the laser oscillation source decreases as the cumulative irradiation time increases, and eventually it becomes impossible to obtain an amount of light sufficient to form a desired image on the irradiation object.

[0004] In response to this, for example, Patent Document 1 (Japanese Patent No. 2915077) describes setting a threshold value for the amount of light or cumulative usage time of the laser, and replacing the laser when this threshold value is exceeded. Summary of the Invention [Problem to be solved by the invention]

[0005] When a plurality of laser irradiation devices irradiate laser beams with different irradiation contents, there is a problem in that the time until the laser irradiation unit reaches the end of its life varies due to differences in the irradiation time for each irradiation content.

[0006] An object of the present invention is to adjust the irradiation time of each laser irradiation unit. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a laser irradiation device having a plurality of laser irradiation units that irradiate laser light, wherein the plurality of laser irradiation units each irradiate the same irradiation object with laser light of a plurality of irradiation contents with different irradiation times, and the irradiation contents irradiated by the laser irradiation units are switched during the process of irradiating the plurality of irradiation objects with laser light. [Effects of the Invention]

[0008] According to the present invention, the irradiation time of each laser irradiation unit can be adjusted. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a laser irradiation device according to a first embodiment of the present invention. [Figure 2] 10 is a schematic diagram showing a storage section transported by a transport section and a laser irradiation section. FIG. [Figure 3] 10(a) to 10(d) are diagrams showing an example of changes in the properties of a container. [Figure 4] 10(a) is a diagram showing the scanning direction of the laser in the scanning range on the container, and FIG. 10(b) is a diagram showing each dot in the scanning range of FIG. 10(a). [Figure 5] FIG. 10 is a diagram showing how each laser irradiation unit draws a respective image on a container. [Figure 6] FIG. 10 is a diagram showing ON / OFF of the lasers of the respective laser irradiation units. [Figure 7] FIG. 2 is a block diagram showing the functional configuration of a control unit according to the first embodiment of the present invention. [Figure 8] 10 is a conceptual diagram showing information on an image to be drawn in a drawing range stored in a storage unit provided in each laser irradiation unit. FIG. [Figure 9] 4 is a flowchart showing a procedure for switching images to be drawn by each laser irradiation unit in the laser irradiation device according to the first embodiment of the present invention. FIG. [Figure 10] 10A and 10B are diagrams showing the process of drawing each image on a container along the time axis in a laser irradiation device different from that of the present invention. [Figure 11] 4A to 4C are diagrams showing, along a time axis, a process of drawing each image on a container in the laser irradiation device according to the first embodiment of the present invention. [Figure 12] 10A to 10C are diagrams showing the process of drawing each image on a container along a time axis in a laser irradiation device according to a second embodiment of the present invention. [Figure 13] 10A to 10C are diagrams showing, along a time axis, the process of drawing each image on a container in a laser irradiation device according to a third embodiment of the present invention. [Figure 14] 10A to 10C are diagrams showing, along a time axis, a process of drawing each image on a container in a laser irradiation device according to a fourth embodiment of the present invention. [Figure 15] FIG. 13 is a flowchart showing a procedure for switching images to be drawn by each laser irradiation unit in a laser irradiation device according to a fifth embodiment of the present invention. [Figure 16] FIG. 16 is a diagram showing the time transition of the cumulative drawing time of each laser irradiation unit in the laser irradiation device of FIG. [Figure 17] FIG. 13 is a diagram showing the time transition of the cumulative drawing time of each laser irradiation unit in the laser irradiation device according to the sixth embodiment of the present invention. [Figure 18] FIG. 13 is a diagram showing the time transition of the cumulative drawing time of each laser irradiation unit in the laser irradiation device according to the seventh embodiment of the present invention. [Figure 19] FIG. 10 is a diagram showing the relationship between cumulative irradiation time and light amount. [Figure 20] FIG. 13 is a flowchart showing a procedure for switching images to be drawn by each laser irradiation unit in a laser irradiation device according to an eighth embodiment of the present invention. [Figure 21] 10A and 10B are diagrams showing an example of timing for switching the drawing content of the pulse laser oscillators of the laser irradiation units. [Figure 22] FIG. 13 is a block diagram showing the functional configuration of a control unit according to an eighth embodiment of the present invention. [Figure 23] FIG. 10 is a diagram showing the relationship between the increase in light intensity due to an increase in the output of a pulse laser oscillator and the cumulative irradiation time. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0011] Fig. 1 is a schematic diagram of a laser irradiation system according to a first embodiment of the present invention, Fig. 2 is a schematic diagram showing a storage section transported by a transport section and a laser irradiation section.

[0012] The laser irradiation system 1000 in Fig. 1 includes a laser irradiation device 1 and a conveying unit 200 (conveying mechanism 200). The laser irradiation device 1 includes a laser irradiation unit 100, a detection unit, and the like. Although only one laser irradiation unit 100 is shown in Fig. 1, the laser irradiation device 1 includes multiple laser irradiation units 100A and 100B as shown in Fig. 2. The laser irradiation device 1 also includes a PC 500 (see Fig. 7) which will be described later.

[0013] <Configuration of laser irradiation device> As shown in FIG. 1 , a laser irradiation unit 100 irradiates a laser (laser light) L onto an irradiation object transported by a transport unit 200. In this embodiment, the irradiation object is a container 50 such as a PET (Poly Ethylene Terephthalate) bottle. When the laser irradiation unit 100 irradiates the container 50 with the laser L, the properties of the container 50 change and a pattern is formed on the surface of the container 50. The pattern formed on the container 50 includes characters, codes such as barcodes, figures, images, etc., and forms information such as the name, identification number, manufacturer, and manufacturing date and time of the items contained in the container 50. The position where the pattern is formed on the container 50 may be the outer surface of the container 50 or the inner surface of the container 50.

[0014] The following describes a first embodiment of a laser irradiation device according to the present invention, its configuration, and a laser irradiation method using the laser irradiation device of the first embodiment. The laser irradiation device of this embodiment forms a pattern on the surface of a container by laser irradiation, but the laser irradiation device according to the present invention can also be applied to forming a pattern on the surface of an irradiation target other than a container.

[0015] <Configuration of the laser irradiation unit> The laser irradiation unit 100 includes a laser oscillation source 11, an optical system 12, a deflection unit 13, and a focusing unit .

[0016] <Laser oscillation source> The laser oscillation source 11 is a means for oscillating a laser L. In this embodiment, a pulsed laser oscillation device 10 is used as the laser oscillation source 11. The pulsed laser oscillation device 10 irradiates the laser L by repeatedly flashing at short time intervals. A continuous wave laser (CW laser) device may be used as the laser oscillation source 11 instead of the pulsed laser oscillation device 10. A continuous wave laser device is a laser oscillation source that continuously oscillates a laser.

[0017] The pulsed laser oscillator 10 emits a substantially parallel pulsed laser beam. The pulsed laser oscillator 10 is configured to be able to switch between oscillation (on) and non-oscillation (off) based on the pattern data formed in the container 50. An example of the pulsed laser oscillator 10 is one capable of switching between three oscillation wavelengths: a fundamental wave with an oscillation wavelength of 1064 nm, a second harmonic with an oscillation wavelength of 532 nm, and a third harmonic with an oscillation wavelength of 355 nm. For example, a pulsed laser oscillator such as the Talisker Ultra355-4 manufactured by Coherent, based on a fiber laser, can be used. The laser pulse width is 15 picoseconds or less at all oscillation wavelengths. The repetition rate of the laser can be selected appropriately from a single shot to 200 kHz. The laser beam diameter is approximately 2.0 mm for the fundamental wave, approximately 1.4 mm for the second harmonic, and approximately 1.3 mm for the third harmonic.

[0018] <Optical system> The optical system 12 is a means for adjusting the beam diameter of the laser L emitted from the laser oscillation source 11. In this embodiment, a beam expander 9 is used as the optical system 12. When a pulsed laser oscillation device 10 is used as the laser oscillation source 11, the beam expander 9 expands the beam diameter of the laser L by a predetermined expansion ratio and emits it as a substantially parallel laser beam.

[0019] <Deflection section> The deflection unit 13 deflects the laser L, the beam diameter of which has been adjusted by the optical system 12. The deflection unit 13 has, for example, a first galvanometer mirror 15 and a second galvanometer mirror 16. Either one of the two galvanometer mirrors may be a polygon mirror. The first galvanometer mirror 15 deflects the laser L, the beam diameter of which has been adjusted by the optical system 12, toward the second galvanometer mirror 16. In addition, the second galvanometer mirror 16 deflects the laser L, which has been deflected by the first galvanometer mirror 15, toward the focusing unit 14.

[0020] The first galvanometer mirror 15 is disposed upstream of the optical axis of the laser L. The first galvanometer mirror 15 deflects the laser L in a direction perpendicular to the incident direction (downward in FIG. 1). The first galvanometer mirror 15 is configured to be swingable by a drive source such as a motor. As the first galvanometer mirror 15 swings, the laser L from the beam expander 9 scans in the transport direction of the irradiation target. For this reason, the control of the scanning by the first galvanometer mirror 15 is determined taking into consideration the transport speed of the container 50.

[0021] On the other hand, the second galvanometer mirror 16 is disposed downstream on the optical axis of the laser L. The second galvanometer mirror 16 scans the laser L in a direction intersecting the scanning direction of the first galvanometer mirror 15 (particularly in the present embodiment, a direction perpendicular to the scanning direction, i.e., the direction of arrow G in FIG. 1).

[0022] <Light collecting part> The focusing unit 14 focuses the laser beam L deflected by the deflection unit 13 onto the container 50. More specifically, the focusing unit 14 focuses the laser beam L onto a predetermined position on the container 50 where the laser beam L is to be irradiated. The focusing unit 14 has, for example, an fθ lens 17 as an imaging optical element. The fθ lens 17 is a lens designed and manufactured so that the scanning speed of the laser beam L passing through the peripheral and central portions is approximately constant. The laser beam L incident on the fθ lens 17 from the deflection unit 13 is focused by the fθ lens 17 and irradiated toward the container 50. The fθ lens 17 may be composed of a single lens or a combination of multiple lenses. The function of the fθ lens 17 may also be realized by a configuration including optical elements other than lenses, such as mirrors.

[0023] <Conveyor device configuration> Next, the configuration of the transport unit 200 will be described.

[0024] As shown in FIG. 2, the conveying unit 200 is a device that conveys the containers 50, such as a belt conveyor. The conveying unit 200 sequentially conveys the containers 50 at predetermined intervals in a conveying direction A (hereinafter simply referred to as the "conveying direction"). A first laser irradiation unit 100A and a second laser irradiation unit 100B are arranged in the conveying direction A. The laser irradiation units 100A and 100B have respective irradiation ranges 101A and 101B, and sequentially irradiate the containers 50 that pass through these ranges 101A and 101B with a laser. The irradiation ranges 101A and 101B are processing ranges in which the laser irradiation units 100A and 100B perform laser processing on the containers 50.

[0025] <Configuration of the transport detection device> Next, the configuration of the transport detection unit 300 will be described.

[0026] The transport detection unit 300 is a device that detects the containers 50 transported by the transport unit 200. The transport detection unit 300 is disposed upstream of the laser irradiation position in the transport direction A. Specifically, the transport detection unit 300 according to this embodiment is configured by an optical sensor including a light-emitting element and a light-receiving element. The light-emitting element and the light-receiving element are disposed upstream of the irradiation ranges 101A and 101B in the transport direction A, on either side of the transport unit 200. However, for convenience, the transport detection unit 300 is shown on only one side of the transport unit 200 in FIG. 2 .

[0027] When the container 50 passes between the light-emitting element and the light-receiving element, the light irradiated from the light-emitting element toward the light-receiving element is blocked by the container 50, and the container 50 is detected. The transport detection unit 300 detects the container 50 and acquires detection information including the time of detection, etc. Then, based on the detection information, the transport distance from the container 50 to the laser irradiation position and the transport speed are calculated. Based on the transport distance and transport speed, the time at which the container 50 enters the laser irradiation position is calculated.

[0028] <Changes in the properties of the container> Next, the change in property of the container 50 due to laser irradiation will be described. Figure 3 is a diagram showing an example of the change in property of the container 50. The property of the container 50 changes in the order of Figure 3(a), (b), (c), and (d) due to laser irradiation. As a result, a pattern is formed on the container 50.

[0029] Fig. 3(a) shows a recessed shape 50a formed by evaporation of the surface of the container 50. Fig. 3(b) shows a recessed shape 50a formed by melting the surface of the container 50. In the case of Fig. 3(b), the peripheral edge of the recessed shape 50a is raised compared to Fig. 3(a).

[0030] 3(c) shows a state change in which the surface of the container 50 is crystallized. FIG. 3(d) shows a state change in which the inside of the container 50 is foamed. By irradiating the container 50 with a CW laser L having a wavelength of 355 nm to 1064 nm, it is also possible to melt the container 50 and form a recess. Furthermore, if the laser L continues to be irradiated even after the container 50 has melted, the inside and surface of the container 50 can be foamed and become cloudy.

[0031] To change the crystallized state, the container 50 is made of, for example, PET, and is irradiated with a CW laser L having a wavelength of 355 nm to 1064 nm to quickly raise the temperature of the container 50. The container 50 is then gradually cooled by, for example, weakening the output of the laser L, thereby bringing the container 50 into a crystallized state and becoming opaque. After the temperature has been raised, if the container is rapidly cooled by, for example, turning off the laser L, the PET becomes amorphous and transparent.

[0032] The change in the properties of the container 50 is not limited to that shown in FIG. 3. The type of resin may be changed from PET to change the properties of the container 50 through yellowing, oxidation, surface modification, or the like. There are no particular limitations on the color or material of the resin constituting the container 50, as long as a pattern can be formed by the laser L. When the container 50 is irradiated with a laser, the container 50 may or may not contain an item. There are also no particular limitations on the type or color of the item contained in the container 50.

[0033] FIG. 4(a) is a diagram showing the scanning direction of the laser in the scanning range on the container, and FIG. 4(b) is a diagram showing each dot in the scanning range of FIG. 4(a). As shown in FIG. 4(a), for example, a scanning range 52 is provided on a container 50. By causing a galvanometer scanner to reciprocate in the main scanning direction across scanning range 52 of a container 50 being transported in the direction of arrow A, starting from the row furthest downstream in the transport direction (the row furthest to the right in FIG. 4(a)), the entire irradiation area of ​​scanning range 52 can be irradiated with a laser. More specifically, while the transport unit transports the container 50 in the direction of arrow A, the galvanometer scanner relatively scans with a laser so that it can reciprocate across scanning range 52 as indicated by the arrows in FIG. 4(a), thereby irradiating the entire irradiation area of ​​scanning range 52 with the laser. As shown in FIG. 2, each laser irradiation unit 100A, 100B performs this series of operations until each container 50 passes through irradiation ranges 101A, 101B as transported by transport unit 200. That is, the container 50 is being transported in the direction of arrow A by the transport unit 200 while the laser irradiation units 100A and 100B are irradiating the laser beams.

[0034] When a galvanometer scanner scans back and forth, it needs to decelerate and accelerate when reversing the scanning direction. Because it is difficult to match the angle of the galvanometer scanner with the corresponding coordinates during this deceleration and acceleration, it essentially becomes non-processing time. For this reason, the productivity of laser processing is increased by making the area of ​​constant-speed operation of the galvanometer scanner as long as possible. In other words, the scanning range is set longer in the main scanning direction than the area actually irradiated with the laser.

[0035] As shown in Figure 4(b), each scanning area (tiny dots) in the scanning range 52, which is arranged at equal intervals in the main scanning direction and sub-scanning direction, can be irradiated with a laser by scanning the galvanometer scanner as the container is transported. This allows any pattern image to be processed at the speed of light. This scanning area includes an irradiation area where the laser is irradiated to form an image, and a non-irradiation area where the laser is not irradiated. In other words, the laser is turned on when passing through an irradiation area, and turned off when passing through a non-irradiation area. Each scanning area does not need to be an area separated by visible lines, but can be a conceptually divided area.

[0036] As shown in FIG. 5 , in the container 50 of this embodiment, a laser scans scanning ranges 52A and 52B to form a first image 53A and a second image 53B, respectively. That is, the first image 53A and the second image 53B are formed at different positions on the container 50. The container 50 is transported in the direction of arrow A by a transport unit, and the first laser irradiation unit 100A irradiates the first scanning range 52A with a laser to form the first image 53A. Further, downstream in the transport direction, the second laser irradiation unit 100B irradiates the second scanning range 52B with a laser to form the second image 53B. In this way, the first laser irradiation unit 100A and the second laser irradiation unit 100B scan the different scanning ranges 52A and 52B of the same container 50 with a laser to form the images 53A and 53B. As a result, images 53A and 53B can be formed on the containers 50 within the limited time it takes for each container 50 to pass through the irradiation range of the first laser irradiation unit 100A or the second laser irradiation unit 100B.

[0037] As shown in FIG. 6, first, the first laser irradiation unit 100A scans the container in the first scanning range 52A to form a first image (i.e., emits light to draw the first image). Then, the second laser irradiation unit 100B scans the container in the second scanning range 52B to form a second image. In each scanning range, the laser irradiation unit repeatedly turns the laser on and off, irradiating only the irradiation area with the laser. The solid vertical lines in FIG. 6 indicate the timing to turn the laser on, and the dotted vertical lines indicate the timing to turn the laser off. This combination is changed for each image to be formed. When the laser is off, the laser pulse is masked to prevent the laser from irradiating the container. In the section between the first scanning range 52A and the second scanning range 52B in FIG. 6, the container 50 moves from the irradiation range of the first laser irradiation unit 100A to the irradiation range of the second laser irradiation unit 100B, completing preparations for forming a second image in the second scanning range 52B of the second laser irradiation unit 100B.

[0038] When forming the first and second images, the second scanning range 52B is wider than the first scanning range 52A and has a larger number of irradiation areas to be irradiated with the laser. In other words, the laser irradiation time is longer for the second scanning range 52B than for the first scanning range 52A. Therefore, if laser processing is continuously performed on multiple containers 50 using the combination shown in FIG. 5, the pulsed laser oscillator of the second laser irradiation unit 100B will reach the end of its life before the first laser irradiation unit 100A and will need to be replaced. During this replacement work, the processing line using the laser irradiation device will be stopped. Therefore, if the pulsed laser oscillators of each laser irradiation unit reach the end of their life at different times as described above, the processing line will be stopped for the number of laser irradiation units, resulting in a decrease in productivity.

[0039] In contrast, in this embodiment, each laser irradiation unit is configured to change the image formed by scanning the laser. That is, during the process in which the containers are sequentially transported by the transport unit and laser processing is performed, the first laser irradiation unit 100A irradiates the second scanning range 52B with a laser to form the second image 53B, and the second laser irradiation unit 100B irradiates the first scanning range 52A with a laser to form the first image 53A. This allows the cumulative irradiation time of the first laser irradiation unit 100A and the second laser irradiation unit 100B to be adjusted. Specifically, the difference in irradiation time between the laser irradiation units can be reduced so that these laser irradiation units reach the end of their lifespans at the same time. This reduces the number of times the processing line needs to be stopped due to replacement of the pulse laser oscillators of the laser irradiation units, thereby improving the productivity of the laser irradiation device.

[0040] In the following description, the above-mentioned "scanning ranges 52A, 52B" are also referred to as "drawing ranges 52A, 52B," which are ranges in which image 1 or image 2 is drawn by laser processing. Furthermore, in this embodiment, "drawing" in the drawing range has the same meaning as "forming an image" in the drawing range, and refers to scanning the laser in the drawing range and irradiating the irradiation area of ​​the drawing range with the laser. In other words, in this embodiment, laser processing of the container is drawing an image on the container, and the "drawing time" by the laser irradiation unit (or laser oscillation source) has the same meaning as "laser irradiation time" or "laser emission time."

[0041] Next, the functional configuration of the control unit will be described with reference to FIG.

[0042] As shown in Figure 7, the control unit provided in the laser irradiation device 1 includes a first FPGA 401 which is a first control unit provided in the first laser irradiation unit 100A, a second FPGA 402 which is a second control unit provided in the second laser irradiation unit 100B, and a PC control unit 403 provided in the PC 500.

[0043] The first FPGA 401 and the second FPGA 402 each include a drawing data input unit 41, a profile data designation unit 42, a storage unit 43, a control data generation unit 44, a laser irradiation control unit 45, a galvano scanner controller 46, and the like.

[0044] The functions of the control data generation unit 44, the laser irradiation control unit 45, and the galvano scanner controller 46 are realized by the FPGAs 401 and 402 executing predetermined programs and outputting control signals to the outside of the FPGAs via the external device connection I / F. The function of the storage unit 43 is realized by a hard disk or the like.

[0045] Drawing data is input to drawing data input unit 41. The drawing data is data on the drawing content to be drawn on the container by laser irradiation device 1. The drawing content (irradiation content) is information on the image to be drawn in the drawing range of the container. This drawing content includes the drawing start position (irradiation start position) and the shape of the image to be drawn, that is, laser ON / OFF information for the number of dots in the drawing range. For example, the drawing content of the first image saved in storage unit 43 includes the fact that the drawing start position is the start position of drawing range 52A (see FIG. 5) of the container (the upper right position of drawing range 52A in FIG. 5).

[0046] The drawing data input unit 41 outputs drawing data input from the PC 500 to the control data generation unit 44 and the profile data specification unit 42. The drawing data input from the drawing data input unit 41 may be temporarily stored in the storage unit 43. Since the drawing data differs depending on the shape of the container, drawing data corresponding to the type of container may be stored in advance in the storage unit 43.

[0047] The profile data designation unit 42 designates profile data from the storage unit 43. The profile data determines the irradiation area and non-irradiation area when irradiating with a laser. The profile data also determines the acceleration when accelerating the speed at which the laser irradiation device 1 operates, the period for acceleration or deceleration, and the constant speed period.

[0048] The profile data is stored in a storage unit 43. The profile data may be stored in advance, or may be stored temporarily during scanning and irradiation.

[0049] The control data generation unit 44 generates control data based on the drawing data from the drawing data input unit 41 and the profile data from the profile data designation unit 42. The control data is data for controlling the laser irradiation device 1. More specifically, the control data includes data for controlling the laser oscillation source 11, the deflection unit 13, etc.

[0050] Furthermore, the control data generating unit 44 outputs the generated control data to a laser irradiation control unit 45 and a galvano scanner controller 46 which is a laser scanning control unit.

[0051] Based on the control data, the laser irradiation control unit 45 controls the irradiation of the laser L emitted from the laser oscillation source 11. Furthermore, the galvano scanner controller 46 receives a signal from the FPGA and controls the deflection unit 13.

[0052] The laser irradiation control unit 45 further includes a light intensity control unit 451 and a pulse control unit 452. The light intensity control unit 451 controls the light intensity of the laser L. The pulse control unit 452 controls the pulse width and irradiation timing of the laser L.

[0053] The galvanometer scanner controller 46 controls the deflection of the laser L by the deflection unit 13 based on the control condition data. Specifically, it controls the on / off of driving the galvanometer mirrors 15 and 16, etc.

[0054] When a container is detected by the transport detection unit 300, that information is input to FPGAs 401 and 402, which determine the timing for starting laser irradiation. In the above explanation, an FPGA is provided in each laser irradiation unit. However, software processing may also be used as long as control data can be corrected in real time.

[0055] Each FPGA may also include a drawing time calculation unit 47. The drawing time calculation unit 47 calculates the time required for the laser oscillation source 11 to draw based on the control data generated by the control data generation unit 44, and adds this to the cumulative drawing time stored up to that point. This cumulative drawing time is input to a display unit 61 provided in the PC 500, and the display unit 61 displays the cumulative drawing time.

[0056] Furthermore, when determining whether to switch the drawing content of each laser irradiation unit based on the cumulative drawing time of each laser irradiation unit (as will be described in detail later), the cumulative drawing time stored in the drawing time calculation unit 47 is input to the other FPGA. As a result, for example, the control data generation unit 44 or the laser irradiation control unit 45 of each FPGA determines whether to switch the drawing content of the laser irradiation units 100A and 100B. However, the switching of the drawing content may also be determined by the PC 500. In this case, the cumulative drawing time stored in the drawing time calculation unit 47 of each FPGA is input to the PC control unit 403.

[0057] The PC control unit 403 provided in the PC 500 includes a drawing data transmission unit 48. The drawing data transmission unit 48 transmits drawing data to the drawing data input units 41 of the laser irradiation units 100A and 100B.

[0058] FIG. 8 is a conceptual diagram showing information on an image to be drawn in a drawing range, which information is stored in a storage unit provided in each laser irradiation unit.

[0059] As shown in Fig. 8, the storage unit 43A of the first laser irradiation unit and the storage unit 43B of the second laser irradiation unit each store data of the drawing content of the first image and the drawing content of the second image. For example, the drawing content of the first image stored in the storage unit 43A includes the drawing start position in the drawing range 52A and information on turning the laser on and off in the order shown in Fig. 4(b) from the drawing start position. The drawing contents are stored in different areas in the storage unit 43 so as not to overlap. The drawing content data is stored in the storage unit 43 by a PC.

[0060] In Fig. 8, the start address of the memory in storage unit 43A is set to the first image. Also, the start address of the memory in storage unit 43B is set to the second image. That is, the first laser irradiation unit draws the first image, and the second laser irradiation unit draws the second image. During laser irradiation, ON / OFF data is read out in order as shown in Fig. 4 from the start address position (the upper right position in Fig. 8) and drawing is performed. When switching the images to be drawn on the container by the first laser irradiation unit and the second laser irradiation unit, the start address of the memory in storage unit 43A is changed to the second image, and the start address of the memory in storage unit 43B is changed to the first image.

[0061] In the above explanation, we have shown a case where only the drawing content (drawing content of the first image and the second image) to be drawn on the container currently being transported is stored in the storage unit, but the drawing content of a third image or a fourth image that is different from the image to be drawn on the container currently being transported may also be stored in advance in the storage unit. This makes it possible to transition to laser processing to draw a new image without stopping the laser processing process, even if the image to be drawn on the container is changed. In this way, drawing content that has been stored in advance in the storage unit can be freely switched.

[0062] Next, a procedure for switching images drawn by each laser irradiation unit in the laser irradiation device according to the first embodiment of the present invention will be described with reference to Fig. 9. In the first embodiment, the first laser irradiation unit and the second laser irradiation unit alternately switch the areas where images are formed.

[0063] As shown in FIG. 9, first, information on the drawing content of each laser irradiation unit is registered in a storage unit or the like (step S1). Then, when the transport detection unit detects the transport of a container (step S2), the control unit transmits the aforementioned signals for performing laser processing. This causes each laser irradiation unit to irradiate the container with laser (step S3). Thereafter, the drawing content to be drawn by each laser irradiation unit is changed (step S4). Thereafter, by repeating steps S2 to S4, the first laser irradiation unit and the second laser irradiation unit alternately switch the drawing content between image 1 and image 2 and irradiate the transported container with laser.

[0064] Furthermore, by switching the drawing content between the laser irradiation units as described above, the time required for laser processing of the container can be shortened, thereby improving the productivity of the laser irradiation device. The time required for laser processing of the laser irradiation device will be explained below.

[0065] 10 is a diagram showing the process of drawing each image on a container along the time axis in a laser irradiation device that does not switch the drawing content between multiple laser irradiation units, unlike the above embodiment. The horizontal axis of FIG. 10 represents time T.

[0066] As shown in Fig. 10, each laser irradiation unit can draw a first image 53A (see Fig. 5) at time T1 and a second image 53B at time T2. Furthermore, "intval" in Fig. 10 is the time from when laser processing of a container starts until when laser processing of the next container starts, and in particular Fig. 10 is shown as the time from when the first laser irradiation unit starts laser processing of a container until when laser processing of the next container starts.

[0067] First, the first laser irradiation unit 100A draws a first image 53A on the transported container 50A at time T1. Then, after an interval of time Tx, the second laser irradiation unit 100B draws a second image 53B on the container 50A at time T2. Time Tx is the time it takes for the container 50A to be transported to the irradiation area of ​​the second laser irradiation unit 100B and for the second laser irradiation unit 100B to be ready to irradiate the laser.

[0068] When the next container 50B is transported, the first laser irradiation unit 100A similarly draws the first image 53A at time T1, and the second laser irradiation unit 100B similarly draws the second image 53B at time T2. Thereafter, this operation is repeated sequentially for each container that is transported.

[0069] In Figure 10, since time T2 is longer than time T1, the first laser irradiation unit 100A has a free time between each laser irradiation, while the second laser irradiation unit 100B performs the next laser irradiation as soon as it becomes possible to perform the next laser irradiation after time Tx has elapsed.

[0070] Here, it takes T1+Tx+T2+Tx from the time when the container 50A is transported into the irradiation range of the first laser irradiation unit 100A, that is, from the time when laser irradiation of the container 50A begins, until the second laser irradiation unit 100B finishes laser processing of the container 50A and becomes ready for the next laser processing. Since intval is the time it takes to perform laser processing on one container 50, the time obtained by adding T1 and Tx to intval must be greater than the aforementioned T1+Tx+T2+Tx. In other words, the following formula (1) must be satisfied. By satisfying formula (1), an intval sufficient to repeatedly perform laser processing is ensured. intval+T1+Tx>T1+Tx+T2+Tx...(1)

[0071] Equation (2) can be obtained from equation (1). In other words, in Fig. 10, the time it takes for the second laser irradiation unit 100B to draw image 53B is long, time T2, so the processing time required by the second laser irradiation unit 100B determines the overall processing time. In other words, from equation (2), the minimum required time for intval is the laser irradiation time T2 by the second laser irradiation unit 100B plus the time Tx until the second laser irradiation unit 100B is ready to emit the next laser beam. intval>Tx+T2 (2)

[0072] Next, with reference to FIG. 11, the process of drawing each image on the container in the laser irradiation device according to the first embodiment of the present invention using the procedure of FIG. 9 will be described along the time axis.

[0073] In this embodiment, the first laser irradiation unit 100A and the second laser irradiation unit 100B alternately switch between images to be drawn on the container 50. Specifically, as shown in FIG. 11 , the first laser irradiation unit 100A first draws a first image 53A on the first container 50A over time T1. Then, after an interval of time TxB1, the second laser irradiation unit 100B draws a second image 53B on the container 50A over time T2. This completes the laser processing of the container 50A.

[0074] Meanwhile, after finishing drawing the first image 53A on the container 50A, the first laser irradiation unit 100A waits a time TxA1 and then draws the second image 53B on the next container 50B over a time T2. After that, after a time TxB2, the second laser irradiation unit 100B draws the first image 53A on the container 50B over a time T1. This completes the laser processing of the container 50B.

[0075] After completing the drawing of the second image 53B on the container 50B, the first laser irradiation section 100A waits for a time TxA2, and then becomes ready to start drawing on the next container 50C.

[0076] As described above, in this embodiment, the first laser irradiation unit 100A and the second laser irradiation unit 100B alternately draw the first image 53A and the second image 53B on the containers that are transported sequentially. In this case, for example, considering the first laser irradiation unit 100A, it takes a time of T1 + TxA1 + T2 + TxA2 from the time that laser irradiation on the two containers 50A and 50B is completed until preparation for the next laser irradiation is complete. Therefore, by satisfying the following formula (3), the time required for the first laser irradiation unit 100A to perform laser processing can be secured. 2intval>T1+TxA1+T2+TxA2...(3)

[0077] Furthermore, in the case of the second laser irradiation unit 100B, it takes time T1 + TxB1 + T2 + TxB2 from the time when the laser irradiation of the two containers 50A and 50B is completed until preparation for the next laser irradiation is complete. Therefore, by satisfying the following formula (4), the time required for the second laser irradiation unit 100B to perform laser processing can be secured. 2intval>T1+TxB1+T2+TxB2...(4)

[0078] Here, if TxA1 and TxA2, or TxB1 and TxB2 are approximately equal, Equation (5) is obtained from equation (3), and equation (6) is obtained from equation (4). intval>(T1+T2) / 2+TxA1...(5) intval>(T1+T2) / 2+TxB1...(6)

[0079] Furthermore, when minimizing the drawing interval, Tx, TxA1, and TxB1 are sufficiently small compared to T1 and T2 that they can be ignored. Therefore, in the case of FIG. 10, intval is determined by the length of time T2, while in the case of the laser irradiation device of this embodiment shown in FIG. 11, intval is determined by the average value of time T1 and time T2. Therefore, the configuration of this embodiment can shorten intval, thereby improving the productivity of the laser irradiation device. The greater the difference between time T1 and time T2, the greater the effect of shortening intval achieved by the configuration of this embodiment. In other words, compared to the case of FIG. 10, intval can be reduced by (T2-T1) / 2 in this embodiment. Methods for reducing intval include, for example, reducing the interval between containers 50 arranged on the conveying unit or increasing the conveying speed of the conveying unit.

[0080] In this way, in a configuration in which each laser irradiation unit simultaneously irradiates a laser, the time required for laser processing of the container can be shortened by switching the drawing content of each laser irradiation unit. This can improve the productivity of the laser irradiation device. "The laser irradiation units simultaneously irradiate a laser" means that at least a part of the time when the laser irradiation units irradiate the laser overlaps, as in the case of the first laser irradiation unit and the second laser irradiation unit in FIG.

[0081] In the laser irradiation device of FIG. 10, for example, it takes a time T1+Tx before starting to form a second image on the first container 50A. In contrast, in the laser irradiation device of FIG. 11, it takes a time T1+TxB1. TxB1 is shorter than Tx because the timing at which laser processing can be performed by the second laser irradiation unit is advanced in FIG. 11 by reducing intval. As described above, in the laser irradiation device of this embodiment, even if the timing of laser processing by the laser irradiation unit changes due to a change in the irradiation content or a change in the timing of intval or the like corresponding to this change, the control unit can perform laser irradiation at the appropriate timing. It can also accommodate changes in the image to be drawn and the drawing start position. Specifically, the position on the container where laser scanning begins, the timing at which pulse oscillation shown in FIG. 6 begins, and the ON / OFF combination (the combination of solid and dotted vertical lines in FIG. 6) can be changed depending on the irradiation content.

[0082] The laser irradiation by each laser irradiation unit is performed at a predetermined timing after the transport detection unit 300 (see FIG. 2) detects the container 50. This predetermined timing may be when a predetermined time has elapsed since the detection, or when a predetermined number of encoder pulses have elapsed. This predetermined time or number of pulses can be calculated from the transport speed of the transport unit 200 and the distance from the detection position on the transport path by the transport detection unit 300 to the upstream end of the irradiation ranges 101A and 101B of the laser irradiation units 100A and 100B.

[0083] In the above description, the two laser irradiation units 100A and 100B are used to draw images 1 and 2 on the container 50. However, the number of laser irradiation units included in the laser irradiation device of the present invention and the number of images drawn on the container 50 are not limited to this.

[0084] For example, the laser irradiation device according to the second embodiment of the present invention shown in FIG. 12 includes three laser irradiation units 100A, 100B, and 100C, and draws images 1 to 3 on a container 50. Image 1 is drawn for irradiation time T1, image 2 for irradiation time T2, and image 3 for irradiation time T3. Each laser irradiation unit changes the drawing content in the order of image 1 → image 2 → image 3 → image 1, and initially, the first laser irradiation unit 100A draws image 1, the second laser irradiation unit 100B draws image 2, and the third laser irradiation unit 100C draws image 3 at their respective predetermined positions. In FIG. 12, each laser irradiation unit draws images with the same drawing content on different containers at the same time.

[0085] In FIG. 12, TxA1 is the time from when the first laser irradiation unit 100A draws image 1 until it can start drawing image 2. TxA2 is the time from when the first laser irradiation unit 100A draws image 2 until it can start drawing image 3. TxA3 is the time from when the first laser irradiation unit 100A draws image 3 until it can start drawing image 1. TxB1 is the time from when the second laser irradiation unit 100B draws image 1 until it can start drawing image 2. TxB2 is the time from when the second laser irradiation unit 100B draws image 2 until it can start drawing image 3. TxB3 is the time from when the second laser irradiation unit 100B draws image 3 until it can start drawing image 1. TxC1 is the time from when the third laser irradiation unit 100C draws image 1 until it can start drawing image 2. TxC2 is the time from when the third laser irradiation unit 100C draws image 2 until it can start drawing image 3. TxC3 is the time from when the third laser irradiation unit 100C draws image 3 until it can start drawing image 1.

[0086] 12, the time required for the first laser irradiation unit 100A to draw on the containers 50A-50C and become ready for the next drawing, i.e., the time required for 3 intval, is T1 + TxA1 + T2 + TxA2 + T3 + TxA3, which must satisfy formula (7). Furthermore, the time required for the second laser irradiation unit 100B to draw on the containers 50A-50C and become ready for the next drawing, i.e., the time required for 3 intval, is T1 + TxB1 + T2 + TxB2 + T3 + TxB3, which must satisfy formula (8). Furthermore, the time required for the third laser irradiation unit 100C to draw on the containers 50A-50C and become ready for the next drawing, i.e., the time required for 3 intval, is T1 + TxC1 + T2 + TxC2 + T3 + TxC3, which must satisfy formula (9). 3intval>T1+TxA1+T2+TxA2+T3+TxA3...(7) 3intval>T1+TxB1+T2+TxB2+T3+TxB3...(8) 3intval>T1+TxC1+T2+TxC2+T3+TxC3...(9)

[0087] Here, when the time between each drawing, TxA1, etc., is at its minimum value, these values ​​are small enough to be ignored compared to the drawing times T1 to T3. Therefore, the following formula (10) can be obtained from each of formulas (7) to (9). In other words, intval can be determined by the average value of each drawing time, and intval can be made shorter than when it is determined by the longest drawing time as in Figure 10. intval>(T1+T2+T3) / 3 (10)

[0088] The order in which images are drawn on the container 50 can be changed as appropriate. For example, in the laser irradiation device according to the third embodiment of the present invention shown in FIG. 13, the drawing order of image 2 and image 3 is reversed compared to FIG. 12. That is, the images are drawn in the order of image 1 → image 3 → image 2 → image 1. TxA4 in FIG. 13 is the time from when the first laser irradiation unit 100A draws image 1 until it can start drawing image 3. TxA5 is the time from when the first laser irradiation unit 100A draws image 3 until it can start drawing image 2. TxA6 is the time from when the first laser irradiation unit 100A draws image 2 until it can start drawing image 1. TxB4 is the time from when the second laser irradiation unit 100B draws image 1 until it can start drawing image 3. TxB5 is the time from when the second laser irradiation unit 100B draws image 3 until it can start drawing image 2. TxB6 is the time from when the second laser irradiation unit 100B draws image 2 until it can start drawing image 1. TxC4 is the time from when the third laser irradiation unit 100C draws image 1 until it can start drawing image 3. TxC5 is the time from when the third laser irradiation unit 100C draws image 3 until it can start drawing image 2. TxC6 is the time from when the third laser irradiation unit 100C draws image 2 until it can start drawing image 1.

[0089] Similarly, in the embodiment of FIG. 13, if the time between each drawing, such as TxA4, is assumed to be negligibly small compared to the drawing time when it is at its minimum value, then equation (10) can be obtained.

[0090] Furthermore, not all laser irradiation units need to switch the drawing content. For example, in the laser irradiation device according to the fourth embodiment of the present invention shown in FIG. 14, the first and second laser irradiation units alternately switch the drawing content between image 1 and image 2, while the third laser irradiation unit always draws image 3 on the container. In this case, if the drawing time for image 3 is not the longest, the intval can be reduced by switching the drawing content of the first and second laser irradiation units, as in the first embodiment of FIG. 11. The other laser irradiation units do not switch the drawing content with any of the other laser irradiation units. However, the other laser irradiation units do not necessarily continue to draw the same image. For example, the other laser irradiation units may continue to draw different serial numbers for each container.

[0091] The timing at which each laser irradiation unit switches the drawing content is not limited to the alternating switching described above. In the laser irradiation device according to the fifth embodiment of the present invention, the drawing content is switched when the difference in irradiation time between the first laser irradiation unit and the second laser irradiation unit becomes large. This configuration will be described using the flowchart in FIG. 15.

[0092] As shown in Fig. 15, in this embodiment, first, information on the drawing content of the image to be drawn in the container and the threshold value for the difference in irradiation time are registered in the register or memory of the storage unit (step S11). After the container is detected by the transport detection unit, laser processing is performed by the first laser irradiation unit (steps S12 and S13). Then, the drawing time by the first laser irradiation unit is measured and saved in the drawing time calculation unit (step S14). The drawing time is the time it takes to irradiate one irradiation area with the laser multiplied by the number of times the laser is turned on.

[0093] Thereafter, laser processing by the second laser irradiation unit, and measurement and storage of the drawing time are similarly performed (steps S15 and S16). Then, the accumulated drawing times of the first laser irradiation unit and the second laser irradiation unit are compared by the FPGA, and it is determined whether the difference is equal to or less than a threshold value (step S17). If the difference in drawing time exceeds the threshold value, the FPGA switches the drawing content between the first laser irradiation unit and the second laser irradiation unit (step S18), and the process returns to step S12. On the other hand, if it is equal to or less than the threshold value, the FPGA determines whether the accumulated drawing time is equal to or less than a limit drawing time (step S19). If it exceeds the limit drawing time, the laser processing is terminated and the pulse laser oscillator is replaced.

[0094] The drawing time is input from the FPGA to the display unit of the PC (see Figure 7) and is notified to the operator by display on the display unit, allowing the operator to estimate in advance when it will be time to replace the pulse laser oscillator.

[0095] Fig. 16 is a diagram showing the transition of the cumulative drawing time of each laser irradiation unit when the drawing content is switched based on a threshold value as in Fig. 15. The horizontal axis of Fig. 16 represents the number x of containers subjected to laser processing, and the vertical axis represents the drawing time y by the laser irradiation unit. In Fig. 16, the dashed dotted line represents the first laser irradiation unit, and the solid line represents the second laser irradiation unit. However, the first laser irradiation unit and the second laser irradiation unit may be reversed.

[0096] As shown in Figure 16, the line y1 = ax + c is the drawing time per container of the first laser irradiation unit a. The line y2 = bx + d is the drawing time per container of the second laser irradiation unit b. Note that the actual drawing times vary, but the equations for these lines can be determined by approximating them using the least squares method or the like. Figure 16 also starts with the drawing time of each laser irradiation unit being 0, so c and d are both 0.

[0097] The drawing time per line of the second laser irradiation unit is longer than the drawing time per line of the first laser irradiation unit, a. Therefore, the difference in drawing time between the two laser irradiation units increases as the number of lines increases. When the number of processed containers reaches n, the difference reaches a threshold value, Δy1. This causes the drawing content of the first laser irradiation unit and the second laser irradiation unit to be switched. Specifically, the difference in irradiation time of the second laser irradiation unit with respect to the first laser irradiation unit is (b-a)x+dc. Therefore, the drawing content can be switched when x=n by satisfying the following formula (11) (only when formula (11) is satisfied): y2−y1=(b−a)n+dc>Δy1···(11)

[0098] When the drawing content is switched, the slope in Figure 16 switches from the number n onwards, with one laser irradiation section having a slope of b and the other laser irradiation section having a slope of a. In other words, the drawing time of one laser irradiation section is y1 = bx + (a - b)n + c, and the drawing time of the other laser irradiation section is y2 = ax + (b - a)n + d.

[0099] Then, when the number of laser beams reaches nmax, at least one of the laser beam irradiation units reaches the limit drawing time tmax, and the pulse laser oscillator of the laser beam irradiation unit is replaced. At this time, Δy1 is set so that the irradiation time between one laser beam irradiation unit and the other laser beam irradiation unit falls within the error δ. In other words, Δy1 is determined so as to satisfy the following formula (12). |y2-y1|=|(a―b)nmax+2(b―a)n+dc|<δ···(12)

[0100] The limit writing time tmax, its error δ, and the respective writing times a and b are known in advance. From these values, the switching timing, i.e., the threshold value Δy1, is determined so as to ultimately satisfy Equation (12). The error δ is, for example, the error in the life of the laser pulse oscillator. However, nmax may also be the average value of the life of the laser pulse oscillator, including the error.

[0101] Furthermore, thresholds may be set so that the drawing content is switched multiple times before the pulse laser oscillator of the laser irradiation unit reaches the limit drawing time. For example, in the laser irradiation device according to the sixth embodiment of the present invention shown in FIG. 17, the drawing content is switched twice, between n1 and n2 laser beams. The thresholds for the first and second switching are Δy1 and Δy2, respectively. However, switching may be performed three or more times. The convergence conditions for these thresholds Δym (m = 1, 2, 3, etc.) are determined by an iterative method or the like so that the drawing time of each laser irradiation unit converges within the range of tmax ± δ for the same number of laser beams.

[0102] In Figure 17, when the number of lines is n1, the difference in irradiation time reaches Δy1, and the drawing content is switched. Thereafter, as the number of lines processed increases, the irradiation times of the first laser irradiation unit and the second laser irradiation unit are reversed, and the difference in irradiation time widens to reach Δy2. Then, the drawing content is switched again, and the limit drawing time is reached when the irradiation times of the first laser irradiation unit and the second laser irradiation unit become approximately the same. This allows the pulse laser oscillators of the first laser irradiation unit and the second laser irradiation unit to be replaced simultaneously.

[0103] The line segments of the first laser irradiation section in FIG. 17 are, from left to right, y1=ax+c, y1=bx+(ab)n1+c, and y1=ax+(ba)n2+(a-b)n1+c, and the line segments of the second laser irradiation section are y2=bx+d, y2=ax+(ba)n1+d, and y2=bx+(ab)n2+(b-a)n1+d. The condition that Δy1 must satisfy is the same as in the previous embodiment, and is given by equation (11). By satisfying the following equation (13) (only when it is satisfied for the first time), the drawing content is switched at x=n2. Furthermore, the following equation (14) can be obtained as the condition for the final nmax number of lines. y1−y2=(b−a)n2+2(a−b)n1+cd>Δy2···(13) |y2―y1|=|(b―a)nmax+2(a―b)n2+2(b―a)n1+d―c|<δ···(14)

[0104] In the laser irradiation device according to the seventh embodiment of the present invention shown in Fig. 18, the drawing content is changed on the container when the number of laser beams reaches n1. As a result, up to the number of laser beams reaches n1, the slope of the first laser irradiation unit is a1 and the slope of the second laser irradiation unit is b1, whereas from the number of laser beams reaches n1 onwards, the slope of the first laser irradiation unit becomes a2 and the slope of the second laser irradiation unit becomes b2, and thereafter, a combination of a2 and b2 is used. In this case, Δy can be set again in the same manner as in Fig. 16, with the position of the number of laser beams reaching n1 as the starting point and the irradiation times at each position as the y-intercepts.

[0105] Specifically, in the range from n1 to n2, the drawing time for n1 is a1n1+c and the slope of the first laser irradiation part is a2, so y1 = a2(x-n1) + a1n1+c = a2x+(a1-a2)n1+c. Also, y2 = b2x+(b1-b2)n1+d. Furthermore, when the difference in drawing time for n2 exceeds Δy2, in the range from n2 to n3, y1 = b2(x-n2) + a2(n2-n1) + a1n1+c = b2x+(a2-b2)n2+(a1-a2)n1+c, y2 = a2x+(b2-a2)n2+(b1-b2)n1+d. Furthermore, when the difference in drawing time exceeds Δy3 at number n3, in the range from number n3 to number nmax, y1 = a2(x-n3) + b2n3 + (a2-b2)n2 + (a1-a2)n1 + c = a2x + (b2-a2)n3 + (a2-b2)n2 + (a1-a2)n1 + c, y2 = b2x + (a2-b2)n3 + (b2-a2)n2 + (b1-b2)n1 + d. The following formulas (15) to (17) can be obtained as the conditions for each threshold and the final nmax number of lines. y1−y2=(a2−b2)n2+(a1−a2−b1+b2)n1+cd>Δy2···(15) y2−y1=(a2−b2)n3+2(b2−a2)n2+(b1−b2−a1+a2)n1+d−c>Δy3···(16) |y2−y1|=|(b2−a2)nmax+2(a2−b2)n3+2(b2−a2)n2+(b1−b2−a1+a2)n1+d−c|<δ···(17)

[0106] In the above explanation, the timing for switching the image content was determined based on the difference in irradiation time between the laser irradiation units. However, it may also be determined based on the amount of laser light emitted by the laser irradiation units. That is, as shown in FIG. 19, the amount of light B decreases as the cumulative irradiation time t increases, and there is a one-to-one correspondence between the irradiation time t and the amount of light B. Therefore, the timing for switching the image content can be determined based on the measured amount of light B. The procedure for switching the image content for the laser irradiation device according to the eighth embodiment of the present invention, configured as described above, will be explained using the flow chart in FIG. 20. As an example, in the pulsed laser oscillation device of this embodiment, the amount of light drops sharply at the irradiation time t1 in FIG. 19.

[0107] As shown in Fig. 20, this embodiment differs from the flow diagram of Fig. 15 in that the light intensity of the pulse laser oscillator of each laser irradiation unit is measured (detected) (steps S24, S26). Also, whether to switch the drawing content is determined based on whether the difference between the measured light intensities is equal to or less than a threshold value (step S28), and if the light intensity becomes equal to or less than the limit value, the laser processing is terminated and the pulse laser oscillator is replaced (step S29).

[0108] Figure 21 shows an example of the timing of switching the drawing content of the pulse laser oscillator of each laser irradiation unit. Figure 21(a) shows the time when drawing has been done on n containers at the time of switching, and Figure 21(b) shows the time when drawing has been done on nmax containers that have reached the end of their life. The upper side of each figure shows the irradiation time and light intensity of the first laser irradiation unit, and the lower side shows the irradiation time and light intensity of the second laser irradiation unit.

[0109] As shown in FIG. 21(a), based on the difference in irradiation time of the images drawn by each laser, the cumulative irradiation time of the first laser irradiation unit at n lines is t1 and the light intensity is B1, while the cumulative irradiation time of the second laser irradiation unit is t2 and the light intensity is B2. When the light intensity B2 minus B1 exceeds the threshold, the drawing content is switched at the number n of lines. This reverses the difference in the image drawing time, and the increase in the irradiation time of the second laser irradiation unit increases. Finally, as shown in FIG. 21(b), the first laser irradiation unit and the second laser irradiation unit converge to within the range of the light intensity Bmin ± error δ at the number nmax of lines.

[0110] FIG. 22 is a block diagram showing the functional configuration of a control unit according to the eighth embodiment of the present invention. As shown in FIG. 22, the laser irradiation device 1 of this embodiment includes a light amount detection unit 62 that detects the light amount of the laser oscillation source 11.

[0111] The basic control configuration of this embodiment is the same as that of the control unit shown in FIG. 7. The control unit of this embodiment differs from that of the embodiment of FIG. 7 in that the FPGA includes a light intensity calculation unit 49 instead of the drawing time calculation unit 47 of FIG. 7. The light intensity calculation unit 49 calculates the light intensity based on the detection result of the light intensity detection unit 62. This calculation result is input to the other FPGA, which determines whether to switch the drawing content. The calculation result of the light intensity calculation unit 49 is input to a display unit 61, and the calculated light intensity is displayed on the display unit 61.

[0112] The light intensity is input from FPGA 401, 402 to display unit 61 of the PC, and is notified to the operator by display on display unit 61. This allows the operator to estimate in advance when it will be time to replace the pulse laser oscillator device.

[0113] Furthermore, when the light intensity of the pulsed laser oscillator decreases, the light intensity can be increased by increasing the output of the pulsed laser oscillator. For example, as shown in Figure 23, by increasing the output of the pulsed laser oscillator, the limit value of the irradiation time (limit drawing time) at which the pulsed laser oscillator needs to be replaced increases from tmax1 to tmax2. When the output of the pulsed laser oscillator is increased in this way, the threshold light intensity is set again according to the changed irradiation time tmax2.

[0114] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0115] In the above embodiment, a configuration has been described in which each laser irradiation unit simultaneously irradiates a laser onto an irradiation object transported by a transport mechanism. However, the present invention is not limited to this. For example, in a plurality of laser irradiation units that irradiate the same irradiation object with a laser at different times, the irradiation content of the laser light emitted by each laser irradiation unit may be switched. This makes it possible to adjust the irradiation time of each laser irradiation unit and average the lifespan of each laser irradiation unit. Furthermore, the irradiation object targeted by the laser irradiation device of the present invention does not need to be configured to be transported by a transport mechanism.

[0116] In the above explanation, we have shown a case where the difference in the lifespan of each laser irradiation unit is only a margin of error, but for laser irradiation units with different lifespans, the irradiation content may be switched so that the timing at which each unit reaches the end of its lifespan approaches.

[0117] The aspects of the present invention are as follows, for example. <1> A laser irradiation device including a plurality of laser irradiation units that irradiate laser light, The plurality of laser irradiation units irradiate the same irradiation object with laser beams having different irradiation contents and irradiation times, respectively, The laser irradiation device is characterized in that the irradiation content irradiated by the laser irradiation unit is switched during the process of irradiating a plurality of irradiation objects with laser light. <2> the laser irradiation unit irradiates laser light onto irradiation objects sequentially transported by a transport mechanism; The plurality of laser irradiation units simultaneously irradiate different irradiation objects with laser light, respectively. <1> The laser irradiation device described above. <3> the laser irradiation unit irradiates laser light onto irradiation objects sequentially transported by a transport mechanism; The timing of laser irradiation of each of the laser irradiation units with respect to the irradiation object is changed in accordance with the switching of the irradiation content. <1> or <2> The laser irradiation device described above. <4> The laser irradiation unit irradiates the irradiation object with laser light and includes another laser irradiation unit that does not switch the irradiation content between the laser irradiation unit and the other laser irradiation unit. <1> from <3> The laser irradiation device according to any one of the preceding claims. <5> A laser irradiation device including a control unit that stores and controls the irradiation content of the laser light irradiated by the laser irradiation unit, The control unit stores the irradiation content different from the irradiation content of the laser light irradiated onto the same irradiation object. <1> from <4> The laser irradiation device according to any one of the preceding claims. <6> The timing for switching the irradiation content irradiated by the plurality of laser irradiation units is determined based on the accumulated irradiation time during which the laser irradiation units irradiate the laser light. <1> from <5> The laser irradiation device according to any one of the preceding claims. <7> a light amount detection unit for measuring the amount of laser light emitted by the laser irradiation unit, The timing for switching the irradiation content irradiated by the plurality of laser irradiation units is determined based on the light amount detected by the light amount detection unit. <1> from <5> The laser irradiation device according to any one of the preceding claims. <8> A threshold is set for the difference in the cumulative irradiation time of the laser beam irradiation among the plurality of laser irradiation units or the difference in the light amount of the laser beam irradiated by the laser irradiation units, and when the threshold is exceeded, the irradiation content irradiated by the plurality of laser irradiation units is switched. <6> or <7> The laser irradiation device described above. <9> When the laser irradiation unit changes the output of the laser light to be irradiated, the threshold value is changed. <8> The laser irradiation device described above. <10> A display unit is provided that displays the cumulative irradiation time or the amount of laser light emitted by the laser irradiation unit. <6> from <9> The laser irradiation device according to any one of the preceding claims. <11> A laser irradiation method in which a plurality of laser irradiation units irradiate a single irradiation object with laser beams having different irradiation times, respectively, comprising: The laser irradiation method is characterized in that, in the process of irradiating a plurality of irradiation objects with laser light, the irradiation content irradiated by each of the laser irradiation units is switched. [Explanation of symbols]

[0118] 1. Laser irradiation device 50 container (irradiation object) 61 Display section 62 Light quantity detection unit 100 Laser irradiation unit 100A First laser irradiation unit 100B Second laser irradiation unit 200 Conveying unit (conveying mechanism) 300 Conveyance detection unit 1000 Laser Irradiation System A. Direction of transport of irradiation object L Laser [Prior art documents] [Patent documents]

[0119] [Patent Document 1] Patent No. 2915077

Claims

1. A laser irradiation device including a plurality of laser irradiation units that irradiate laser light, The plurality of laser irradiation units irradiate the same irradiation object with laser beams having different irradiation contents and irradiation times, respectively, A laser irradiation device characterized in that the irradiation content irradiated by the laser irradiation unit is switched during the process of irradiating a plurality of irradiation objects with laser light.

2. the laser irradiation unit irradiates laser light onto irradiation objects sequentially transported by a transport mechanism; 2. The laser irradiation device according to claim 1, wherein the plurality of laser irradiation units simultaneously irradiate different irradiation objects with laser light, respectively.

3. the laser irradiation unit irradiates laser light onto irradiation objects sequentially transported by a transport mechanism; 2. The laser irradiation device according to claim 1, wherein timings of laser irradiation of the object to be irradiated by each of the laser irradiation units are changed in response to the changeover of the irradiation content.

4. 2. The laser irradiation device according to claim 1, further comprising another laser irradiation unit that irradiates an irradiation object with laser light and does not switch the irradiation content between the laser irradiation unit and the other laser irradiation unit.

5. A laser irradiation device including a control unit that stores and controls the irradiation content of the laser light irradiated by the laser irradiation unit, 2. The laser irradiation device according to claim 1, wherein the control unit stores the irradiation content different from the irradiation content of the laser light to be irradiated onto the same irradiation object.

6. 2. The laser irradiation device according to claim 1, wherein timing for switching the irradiation content irradiated by the plurality of laser irradiation units is determined based on an accumulated irradiation time during which the laser irradiation units irradiate the laser light.

7. a light amount detection unit for measuring the amount of laser light emitted by the laser irradiation unit, 2. The laser irradiation device according to claim 1, wherein timing for switching the irradiation content irradiated by the plurality of laser irradiation units is determined based on the light amount detected by the light amount detection unit.

8. 8. The laser irradiation device according to claim 6 or 7, wherein a threshold value is set for the difference in cumulative irradiation time for irradiating laser light among the plurality of laser irradiation units, or the difference in light amount of laser light irradiated by the laser irradiation units, and when the threshold value is exceeded, the irradiation content irradiated by the plurality of laser irradiation units is switched.

9. 9. The laser irradiation device according to claim 8, wherein the threshold value is changed when the output of the laser irradiation unit for irradiating the laser light is changed.

10. 8. The laser irradiation device according to claim 6, further comprising a display unit that displays the cumulative irradiation time or the amount of laser light irradiated by said laser irradiation unit.

11. A laser irradiation method in which a plurality of laser irradiation units irradiate a single irradiation object with laser beams having different irradiation times, respectively, comprising: A laser irradiation method, characterized in that, in the process of irradiating a plurality of irradiation objects with laser light, the irradiation content irradiated by each of the laser irradiation units is switched.

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