Laser irradiation device, laser irradiation method, laser irradiation system and workpiece

Abstract

To improve laser irradiation accuracy.SOLUTION: A laser irradiation device irradiates an irradiation region 21 of workpiece 1 to be conveyed with a laser beam, wherein among scanning directions crossing each other, a direction with a long scanning distance in one scanning is set to be a main scanning direction, and a direction crossing the main scanning direction is set to be a sub-scanning direction, and the irradiation region 21 whose size in the main scanning direction is equal to or more than the size in the sub-scanning direction is irradiated with a laser beam so that the main scanning direction becomes a direction along a conveyance direction F of the workpiece 1.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a laser irradiation device, a laser irradiation method, a laser irradiation system, and a workpiece.

Background Art

[0002] Laser irradiation devices that irradiate workpieces such as PET (Poly Ethylene Terephthalate) bottles with laser light to form image patterns such as characters are known.

[0003] Laser scanning methods used in such laser irradiation devices include a raster scanning method in which laser light is repeatedly scanned in parallel lines regardless of the shape of the image pattern, and a vector scanning method in which laser light is scanned following the shape of the image pattern.

[0004] For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-55324) discloses the configuration of a raster scanning type laser marking device that performs laser irradiation on an irradiated object being conveyed.

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, the problem of a decrease in the laser irradiation accuracy with respect to the irradiated object when vibrations or speed fluctuations occur in the irradiated object during conveyance has not been studied.

[0006] Therefore, an object of the present invention is to improve the laser irradiation accuracy.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides a laser irradiation device that irradiates a laser on an irradiation region of a workpiece to be conveyed, comprising: a laser oscillation source that oscillates the laser; and scanning means that two-dimensionally scans the laser oscillated from the laser oscillation source in scanning directions that intersect each other in the irradiation region. Among the scanning directions that intersect each other, when the direction with a longer scanning distance in one scan is defined as the main scanning direction and the direction intersecting the main scanning direction is defined as the sub-scanning direction, the scanning means scans the laser such that the main scanning direction is along the conveyance direction of the workpiece with respect to the irradiation region where the size in the main scanning direction is equal to or larger than the size in the sub-scanning direction.

Advantages of the Invention

[0008] According to the present invention, the laser irradiation accuracy can be improved.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and the description thereof will be omitted after being explained once.

[0011] <Overall Configuration of Laser Irradiation System> FIG. 1 is a side view of a laser irradiation system according to a first embodiment of the present invention, and FIG. 2 is a plan view of the laser irradiation system according to the first embodiment of the present invention.

[0012] As shown in FIG. 1, the laser irradiation system 1000 includes a laser irradiation device 100, a conveying means 200, a control unit 400, and the like. In FIG. 2, a conveying position detection means 300 included in the laser irradiation system 1000 is further shown.

[0013] The laser irradiation device 100 is a device that irradiates a workpiece to be conveyed by the conveying means 200 with a laser (laser light) L. Hereinafter, the workpiece will be described as a container 1 made of a transparent resin such as a PET bottle, but the workpiece is not limited to the container 1.

[0014] When the laser L is irradiated from the laser irradiation device 100 onto the surface of the container 1, the properties of the surface portion irradiated with the laser L change, and an image pattern is formed. The image pattern includes codes such as characters and barcodes, figures, images, etc., and indicates information such as the name, identification number, manufacturer, and manufacturing date and time of the contents contained in the container 1, for example. The surface of the container 1 on which the image pattern is formed may be the outer surface of the container 1 or the inner surface of the container 1.

[0015] The conveying means 200 is a means for conveying the container 1. The conveying means 200 is constituted by a conveying device such as a belt conveyor that conveys the container 1 at a constant speed, for example. When the container 1 conveyed by the conveying means 200 reaches the laser irradiation area U on the conveying path 20, the laser L is irradiated from the laser irradiation device 100 toward the container 1. As a result, the laser irradiation location on the container 1 is denatured, and an image pattern is formed.

[0016] The conveyance position detection means 300 is a means for detecting the position of the container 1 upstream of the laser irradiation area U in the conveyance direction F. The conveyance position detection means 300 is constituted by, for example, an optical sensor having a light emitting element 301 and a light receiving element 302. When the conveyed container 1 passes between the light emitting element 301 and the light receiving element 302, the light irradiated from the light emitting element 301 to the light receiving element 302 is blocked, whereby the position of the container 1 is detected.

[0017] The control unit 400 is a computer or a device having a function equivalent to that of a computer that controls the operation of the entire laser irradiation system 1000 including the laser irradiation device 100 and the conveying means 200. For example, the control unit 400 controls the laser irradiation timing of the laser irradiation device 100 based on the detection result of the conveyance position detection means 300. Specifically, when the container 1 passes between the light emitting element 301 and the light receiving element 302, a detection signal is transmitted from the conveyance position detection means 300 to the control unit 400, and the control unit 400 calculates the timing at which the container 1 enters the laser irradiation area U based on the received detection signal. Then, the control unit 400 controls the laser irradiation device 100 based on the calculated timing, and the laser L is irradiated from the laser irradiation device 100 to the container 1. As a result, an image pattern is formed on the container 1. When the laser L is irradiated to the container 1, the container 1 may be in a state of containing the contents or not containing the contents. Also, the type or color of the contents contained in the container 1 is not particularly limited.

[0018] <Configuration of Laser Irradiation Device> Next, based on FIGS. 1 and 2, the configuration of the laser irradiation apparatus according to the first embodiment of the present invention will be described.

[0019] The laser irradiation apparatus 100 includes a laser oscillation source 11, an optical system 12, scanning means 13, and condensing means 14.

[0020] Examples of the laser oscillation source 11 include a pulsed laser oscillation source, a continuous laser (CW laser) oscillation source, and the like. In the following description, the laser oscillation source 11 will be described as a pulsed laser oscillation source 10.

[0021] The pulsed laser oscillation source 10 is an oscillation source that oscillates a substantially parallel pulsed laser beam. Further, the pulsed laser oscillation source 10 is configured to be able to switch between oscillation (on) and non-oscillation (off) based on the data of the image pattern formed in the container 1. As an example of the pulsed laser oscillation source 10, one that can switch between lasers having three oscillation wavelengths, namely, 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], can be mentioned. For example, a pulsed laser oscillation source such as Talisker Ultra355-4 manufactured by Coherent based on a fiber laser can be applied. The pulse width of the laser is 15 [picoseconds] or less at any oscillation wavelength. The repetition frequency of the laser can be appropriately selected in the range from single shot to 200 [kHz]. Also, the beam diameter of the laser 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.

[0022] The optical system 12 has a function of adjusting the beam diameter of the laser L oscillated from the pulsed laser oscillation source 10. In the first embodiment of the present invention, as an example of the optical system 12, a beam expander 9 is used. The beam expander 9 expands the beam diameter of the laser L oscillated from the pulsed laser oscillation source 10 at a predetermined magnification and emits it as a substantially parallel laser beam.

[0023] The scanning means 13 is means for deflecting and scanning the laser L whose beam diameter has been adjusted by the optical system 12. In the first embodiment of the present invention, as an example of the scanning means 13, a galvanometer scanner having a first galvanometer mirror 15 and a second galvanometer mirror 16 is used. Note that either one of the two galvanometer mirrors 15 and 16 may be a polygon mirror. The first galvanometer mirror 15 is disposed upstream of the second galvanometer mirror 16 in the optical axis direction, and deflects the laser L whose beam diameter has been adjusted by the optical system 12 toward the second galvanometer mirror 16. Further, the second galvanometer mirror 16 deflects the laser L deflected by the first galvanometer mirror 15 toward the condensing means 14. As a result, the laser L is secondarily scanned in two directions, a direction along the conveyance direction F (see FIG. 2) of the container 1 and a direction G (see FIG. 1) intersecting therewith.

[0024] The condensing means 14 is means for condensing the laser L deflected by the scanning means 13. In the first embodiment of the present invention, as an example of the condensing means 14, an fθ lens 17 is used. The fθ lens 17 is a lens designed and manufactured such that the scanning speeds of the laser L passing through the peripheral portion and the central portion are substantially constant. When the laser L deflected by the scanning means 13 enters the fθ lens 17, the laser L is condensed by the fθ lens 17 and irradiated onto the surface of the container 1. The fθ lens 17 may be composed of one lens, or may be composed of a combination of a plurality of lenses. Further, the function of the fθ lens 17 may be realized by a configuration including optical elements other than lenses such as mirrors.

[0025] <Configuration of the control unit> Subsequently, based on FIGS. 3 and 4, the configuration of the control unit according to the first embodiment of the present invention will be described. FIG. 3 is a block diagram showing the hardware configuration of the control unit according to the first embodiment of the present invention. FIG. 4 is a block diagram showing the functional configuration of the control unit according to the first embodiment of the present invention.

[0026] As shown in FIG. 3, the control unit 400 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, an HD (Hard Disk) 404, an HDD (Hard Disk Drive) controller 405, and a display 406. Further, the control unit 400 includes an external device connection I / F (Interface) 408, a network I / F 409, a bus line 410, a keyboard 411, a pointing device 412, a DVD-RW (Digital Versatile Disk Rewritable) drive 414, and a media I / F 416.

[0027] The CPU 401 is a processor that controls the operation of the entire control unit 400. The ROM 402 is a memory that stores programs used for driving the CPU 401, such as an IPL (Initial Program Loader).

[0028] The RAM 403 is a memory used as a work area for the CPU 401. The HD 404 is a memory that stores various data such as programs. The HDD controller 405 controls the reading and writing of various data to and from the HD 404 according to the control of the CPU 401.

[0029] The display 406 displays various information such as a cursor, menu, window, characters, or images. The external device connection I / F 408 is an interface for connecting various external devices. The external devices in this case are a laser oscillation source 11 (pulse laser oscillation source 10), scanning means 13 (galvano mirrors 15, 16), a conveyance position detection means 300, etc. However, other devices such as a USB (Universal Serial Bus) memory or a printer can also be connected.

[0030] The network I / F 409 is an interface for data communication using a communication network. The bus line 410 is an address bus, a data bus, or the like for electrically connecting each component such as the CPU 401.

[0031] The keyboard 411 is a type of input means having a plurality of keys for inputting characters, numerical values, various instructions, and the like. The pointing device 412 is a type of input means for selecting various instructions, executing them, selecting a processing target, moving a cursor, and the like.

[0032] The DVD-RW drive 414 controls reading and writing of various data with respect to the DVD-RW 413 as an example of a removable recording medium. Note that the storage medium is not limited to the DVD-RW. The media I / F 416 controls reading and writing (storage) of data with respect to the recording medium 415 such as a flash memory.

[0033] Each piece of hardware constituting these control units 400 does not necessarily have to be all provided. Depending on the form in which the laser irradiation device 100 is used, there may be hardware that is not provided. Also, the laser irradiation device 100 may include all of the hardware and functional configurations of the control unit 400, or a part of the hardware and functional configurations may be connected outside the laser irradiation device 100.

[0034] Also, as shown in FIG. 4, the control unit 400 includes an irradiation data input unit 41, a profile data specifying unit 42, a storage unit 43, a control data generation unit 44, a laser irradiation control unit 45, and a laser scanning control unit 46.

[0035] The functions of the control data generation unit 44, the laser irradiation control unit 45, and the laser scanning control unit 46 are realized by the CPU 401 executing a predetermined program and outputting a control signal via the external device connection I / F 408. However, an electronic circuit or an electric circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) may be added to the hardware configuration of the control unit 400, and part or all of the functions of each component may be realized by the electronic circuit or the electric circuit. The function of the storage unit 43 is realized by the HD 404 or the like.

[0036] Irradiation data input unit 41 receives the irradiation data of the laser L irradiated by the laser irradiation device 100. The irradiation data is input by the user using the keyboard 411 or the pointing device 412 of the control unit 400. The irradiation data includes data related to the image pattern formed on the container 1, as well as other data necessary for laser irradiation. Further, the irradiation data may be recorded in an external device such as a PC (Personal Computer) or a scanner.

[0037] The irradiation data input unit 41 outputs the input irradiation data to each of the control data generation unit 44 and the profile data specifying unit 42. Further, the irradiation data output from the irradiation data input unit 41 may be temporarily stored in the storage unit 43. In that case, the irradiation data corresponding to the shape or type of the container 1 may be stored in the storage unit 43 in advance.

[0038] The profile data specifying unit 42 specifies the profile data from the storage unit 43. The profile data determines the irradiation area and the non-irradiation area when irradiating the laser. Further, the profile data determines the acceleration, the acceleration or deceleration period, and the constant speed period when accelerating the operating speed of the laser irradiation device 100.

[0039] In addition, the profile data is stored in the storage unit 43. The process of storing the profile data may be performed in advance, or may be temporarily performed during the scanning and irradiation of the laser L.

[0040] The control data generation unit 44 generates control data based on the irradiation data from the irradiation data input unit 41 and the profile data of the profile data specifying unit 42. The control data is data for controlling the laser irradiation device 100. More specifically, the control data includes data for controlling the laser oscillation source 11, the scanning means 13, and the like.

[0041] In addition, the control data generation unit 44 outputs the generated control data to the laser irradiation control unit 45 and the laser scanning control unit 46.

[0042] The laser irradiation control unit 45 controls the irradiation of the laser L oscillated from the laser oscillation source 11 based on the control data. Further, the laser scanning control unit 46 controls the scanning means 13 based on the detection information detected by the conveyance position detection means 300.

[0043] When the laser oscillation source 11 is composed of a plurality of pulse laser oscillation sources 10, the laser irradiation control unit 45 performs independent control for each of the plurality of pulse lasers.

[0044] The laser irradiation control unit 45 further includes an optical intensity control unit 451 and a pulse control unit 452. The optical intensity control unit 451 controls the optical intensity of the laser L. The pulse control unit 452 controls the pulse width and irradiation timing of the laser L.

[0045] The laser scanning control unit 46 controls the deflection of the laser L by the scanning means 13 based on the control condition data. Specifically, control such as turning on or off the driving of the galvanometer mirrors 15 and 16 is performed.

[0046] <Change in the properties of the workpiece> FIG. 5 is a diagram showing the mode of the modified portion formed in the container 1 by laser irradiation.

[0047] When the surface of the container 1 is irradiated with the laser L from the laser irradiation device 100, the surface of the container 1 is denatured to form the denatured portion 2. FIG. 5(a) is a diagram showing a mode in which the surface of the container 1 is evaporated by the irradiation with the laser L, and the concave denatured portion 2 is formed. On the other hand, FIG. 5(b) shows the denatured portion 2 when the surface of the container 1 is melted. In the case of FIG. 5(b), compared with FIG. 5(a), the peripheral portion of the concave denatured portion 2 has a raised shape. Further, FIG. 5(c) shows the mode of the denatured portion 2 in which the surface of the container 1 is crystallized, and FIG. 5(d) is a diagram showing the mode of the denatured portion 2 formed by foaming a part of the container 1. In such various denatured portions 2, since the surface roughness is larger than that of the non-laser irradiation portion on the container 1, the light diffusibility is enhanced and the visibility is improved. Thereby, a visible image pattern is formed on the surface of the container 1.

[0048] In order to form the denatured portion 2 by evaporation, as the laser oscillation source 11, it is preferable to use a pulsed laser oscillation source 10 having a wavelength of 355 [nm] or more and 1064 [nm] or less and a pulse width of 10 [fs] or more and 500 [nm] or less. Further, when a continuous laser (CW laser) oscillation source having a wavelength of 355 [nm] or more and 1064 [nm] or less is used as the laser oscillation source 11, the denatured portion 2 by melting can be formed. Furthermore, if the laser L is continuously irradiated even after melting, the surface or the subsurface of the container 1 can be foamed to form the denatured portion 2 which is whitened. In order to form the crystallized denatured portion 2, for example, it is preferable to irradiate the PET container 1 with a CW laser having a wavelength of 355 [nm] or more and 1064 [nm] or less to rapidly increase the temperature of the laser irradiation portion on the container 1. Thereafter, by gradually lowering the temperature of the laser irradiation portion while weakening the power of the irradiated laser L, the crystallized and whitened denatured portion 2 can be obtained. Note that if the irradiation with the laser L is suddenly stopped after raising the temperature of the laser irradiation portion, the temperature of the laser irradiation portion rapidly drops to a transparent amorphous state, so that the whitened denatured portion 2 cannot be obtained.

[0049] In addition to forming the turbid modified portion 2, a part of the surface of the container 1 may be yellowed, or the properties may be changed by an oxidation reaction or surface modification or the like to form the modified portion 2. Further, an absorbent (conversion material) that converts light energy into thermal energy may be applied in advance to the surface of the container 1, and uneven modified portions 2 may be formed on the surface of the container 1 by the thermal energy converted when the laser L is irradiated.

[0050] Further, by adjusting the light energy of the laser L irradiated to the container 1, the size of the beam of the laser L, the irradiation time, etc., the size, shape, depth, etc. of the modified portion 2 can be changed. Also, although the cross-sectional intensity distribution of the laser L is generally a Gaussian distribution, the intensity distribution can be adjusted by combining lasers of an array light source, or a top-hat-shaped intensity distribution with a flat central intensity distribution can be generated by designing the irradiation optical system. Further, the irradiation size of the laser L is adjusted by the laser oscillation source 11 and the optical system 12, and it is preferable to make the irradiation size of the laser L substantially constant in processing. Here, "constant" means that there is substantially no fluctuation within the allowable range of processing accuracy, and includes those that fluctuate within an allowable range of about several percent depending on the processing accuracy.

[0051] <Problems of Laser Irradiation> Here, the problems in the case of laser-irradiating the container during conveyance will be described.

[0052] FIGS. 31(a) and (b) are diagrams showing modes in the case of laser-irradiating using a laser irradiation apparatus according to a comparative example different from the present invention.

[0053] In the comparative example, first, as shown in FIG. 31(a), when the container 1 is conveyed and the irradiation region 21 of the container 1 reaches the laser irradiation position E, the irradiation region 21 is irradiated with a laser to form a single image line 30a. In this case, since the laser is scanned in a direction intersecting or orthogonal to the conveyance direction F of the container 1, a vertical image line 30a is formed. Here, the "irradiation region" refers to the region where the image pattern 31 is formed and is a region that coincides with the shape of the image pattern 31. Therefore, the "irradiation region" does not have to be a region partitioned by a visible line or the like, and it suffices that it is a conceptually partitioned region. Also, the "irradiation region" in the following description means the same region.

[0054] Subsequently, the container 1 is conveyed. As shown in FIG. 31(b), when the irradiation region 21 of the container 1 is displaced by one line (by the width of one image line) in the conveyance direction F with respect to the laser irradiation position E, the laser is again scanned and irradiated in the vertical direction (a direction intersecting or orthogonal to the conveyance direction F). As a result, a new image line 30b is formed adjacent to the previously formed image line 30a. Thereafter, similarly, as the container 1 is conveyed and moved, the laser is scanned, and image lines are sequentially formed in the irradiation region 21.

[0055] In this way, a two-dimensional image pattern is formed by combining one-dimensional scanning of the laser in the vertical direction and conveyance movement of the container 1 in the horizontal direction. However, in the case of such a laser irradiation method, there is a problem that if the conveyance speed fluctuates or vibration occurs in the conveyance direction during laser irradiation on the container 1, the interval between adjacent image lines changes.

[0056] That is, when the laser is scanned and irradiated at a scanning line period Tm [s] with respect to the container 1 conveyed at a constant conveyance speed of V [mm / s], as shown in Fig. 32(a), the image lines 30 are formed at the same intervals of V·Tm [mm]. However, when there are fluctuations in the conveyance speed or vibrations in the conveyance direction, as shown in Figs. 32(b) and (c), the intervals between the image lines 30 become larger or smaller than V·Tm [mm]. At this time, when the speed fluctuation δV(t) of the conveyance speed changes as shown in Fig. 33, the error δPitch in the intervals between the image lines 30 for each scanning line period Tm is expressed by the following formula (1).

[0057] [Number]

[0058] In Fig. 33, when the fluctuation of the conveyance speed is (+), as shown in Fig. 32(b), the interval between the image lines 30 becomes larger by the error δPitch. Conversely, when the fluctuation of the conveyance speed is (-), as shown in Fig. 32(c), the interval between the image lines 30 becomes smaller by the error δPitch. In addition, the error δPitch in the intervals between the image lines 30 can occur not only when there are fluctuations in the conveyance speed but also when there are vibrations in the conveyance direction with respect to the container 1.

[0059] As described above, in the comparative example, when there are fluctuations or vibrations in the conveyance speed, there is a problem that the intervals between the image lines 30 vary, and the laser irradiation accuracy with respect to the container 1 decreases. In addition, when there are variations in the intervals between adjacent image lines 30, there are dense and sparse portions of the image lines 30, and this is recognized as density unevenness in the image pattern.

[0060] Therefore, in the present invention, in order to improve the laser irradiation accuracy with respect to the container 1, the following laser irradiation device, laser irradiation system, and laser irradiation method are proposed. Hereinafter, taking the first embodiment of the present invention as an example, the characteristic parts of the present invention will be described.

[0061] [Characteristic parts of the present invention] FIG. 6 is a diagram showing a mode in the case where a container is irradiated with a laser using the laser irradiation apparatus according to the first embodiment of the present invention.

[0062] As shown in FIG. 6, in the first embodiment of the present invention, the scanning direction of the laser is different from that of the comparative example. That is, in the first embodiment of the present invention, an image line 30 (image pattern 31) is formed with the direction along the conveyance direction F of the container 1 as the scanning direction of the laser.

[0063] Here, in the first embodiment of the present invention, since the pulse laser oscillator 10 is used as the laser oscillator 11, when the laser is scanned in the direction along the conveyance direction F by the scanning means 13, as shown in FIG. 7, minute modified portions 2 are continuously arranged along the conveyance direction F to form an image line 30 (image pattern 31). At this time, even if the conveyance speed of the container 1 fluctuates or vibration in the conveyance direction occurs, since the laser scanning direction is the direction along the conveyance direction F, the irradiation accuracy of the laser is less likely to be affected by the fluctuation or vibration of the conveyance speed. For this reason, it is possible to suppress the variation in the interval Pm between adjacent modified portions 2, and it is also possible to suppress the variation in the overall length of the image line 30.

[0064] For example, in the comparative example, when it is desired to form a plurality of image lines 30 at an interval of 100 [μm], if a speed fluctuation or vibration of the container 1 occurs during laser irradiation, an error δPitch of about 50 [μm] occurs in the interval between the image lines 30. In this case, the interval between the image lines 30 is shifted by 50 [%] with respect to the original interval of 100 [μm]. On the other hand, in the first embodiment of the present invention, when the image line 30 is formed to have a length of 50 [mm], the variation in the length of each image line 30 is 50 [μm], and the ratio of the variation with respect to the overall length of the image line 30 is 0.1% (50 [μm] / 50 [mm] × 100 = 0.1 [%]). Thus, in the first embodiment of the present invention, compared with the comparative example, it is less likely to be affected by speed fluctuations or vibrations, so that an image pattern can be formed with high accuracy, and the quality of the image pattern can be improved.

[0065] As shown in Fig. 8(a), the scanning direction I of the laser may be the same as the conveying direction F, or as shown in Fig. 8(b), the scanning direction I of the laser may be opposite to the conveying direction F. Further, the scanning direction I is not necessarily limited to being parallel to the conveying direction F, and may be a direction slightly inclined with respect to the conveying direction F. Specifically, even when the scanning direction I is inclined by ±10° with respect to the conveying direction F, the effects of the present invention can be achieved. That is, in the present invention, as the mode of "the laser is scanned in the direction along the conveying direction", in addition to the case where the scanning direction I is the same as the conveying direction F and the case where it is opposite to the conveying direction F, the case where the scanning direction I is parallel to the conveying direction F and the case where it is inclined by ±10° with respect to the conveying direction F are also included.

[0066] As described above, in the present invention, the scanning direction I may be any direction along the conveying direction F. However, when the laser is reciprocally scanned along the conveying direction F, the interval Pm between adjacent modified portions 2 may be different between the forward path and the return path. That is, as shown in Fig. 8(a), when the scanning direction I is the same as the conveying direction F, assuming the conveying speed is V [m / s], the scanning speed is Vm [m / s], and the frequency is f [Hz], the interval Pm between adjacent modified portions 2 is Pm = (Vm + V) / f. As shown in Fig. 8(b), when the scanning direction I is opposite to the conveying direction F, assuming the conveying speed is V [m / s], the scanning speed is Vm [m / s], and the frequency is f [Hz], the interval Pm between adjacent modified portions 2 is Pm = (Vm - V) / f. Thus, even when the scanning speed V and the frequency f of the laser are the same, the interval Pm between adjacent modified portions 2 is different depending on whether the scanning direction I is the same as or opposite to the conveying direction F. Therefore, when the laser is reciprocally scanned along the conveying direction F, it is preferable to set the scanning speed or the frequency of the laser so that the interval Pm between adjacent modified portions 2 is the same in the forward path and the return path (Pm = (Vm + V) / f = (Vm - V) / f). This eliminates the variation in the interval Pm between the modified portions 2 and can improve the quality of the image pattern.

[0067] <An example of the scanning path> FIG. 9 is a diagram showing an example of a scanning path when a laser reciprocally scans along the conveyance direction F in the first embodiment of the present invention.

[0068] In the case of FIG. 9, in the irradiation region 21 of the container 1, first, the laser is scanned and irradiated at a constant speed in the same direction as the conveyance direction F, the arrow J1. Then, when the laser reaches one end of the irradiation region 21, in the region outside the irradiation region 21, the laser is reversely scanned like the arrow J2. At this time, the reverse scanning is performed such that the scanning speed decelerates and then accelerates so that the subsequent scanning speed becomes constant. Subsequently, the laser is scanned and irradiated at a constant speed in the direction of the arrow J3 opposite to the conveyance direction F in the irradiation region 21. Then, when the laser reaches the other end of the irradiation region 21, in the region outside the irradiation region 21, the laser is reversely scanned like the arrow J4 in the same manner as the previous reverse scanning. Thereafter, the reciprocating scanning of the laser is repeatedly performed in the same manner, and the laser is sequentially irradiated from the upper part to the lower part of the irradiation region 21 to form an image pattern.

[0069] Thus, in the present invention, a two-dimensional image pattern can be formed by repeatedly performing laser scanning in the conveyance direction F in a direction intersecting the conveyance direction F. Here, among the scanning directions intersecting each other, the direction in which the scanning distance is long in one scanning is defined as the "main scanning direction", and the direction intersecting the main scanning direction is defined as the "sub-scanning direction". In the present invention, the main scanning direction is along the conveyance direction F. Thereby, since the laser irradiation is less affected by speed fluctuations or vibrations, accurate laser irradiation can be performed.

[0070] <Productivity of Image Pattern> Subsequently, the productivity of the image pattern will be described.

[0071] Even when forming an image pattern of the same area on the container, the shorter the time required to form the image pattern on one container, the higher the productivity. Here, the time ta [s] required to form an image pattern on one container is represented by the following formula (2).

[0072]

Number

[0073] In the above formula (2), "vs" is the scanning speed [m / s] in the main scanning direction of the laser in the irradiation region 21, "rf" is the resolution in the sub-scanning direction of the image pattern (the variation in the interval between adjacent modification portions 2 in the direction intersecting the conveyance direction F) [dpi], "tr" is the time [s] required for reverse scanning, "Ls" is the size [m] of the irradiation region or the image pattern in the main scanning direction, and "Lf" is the size [m] of the irradiation region or the image pattern in the sub-scanning direction.

[0074] Here, as shown in Fig. 10(a), in the case of the irradiation region 21A where the size Ls in the main scanning direction is larger than the size Lf in the sub-scanning direction, and conversely, as shown in Fig. 10(b), in the case of the irradiation region 21B where the size Lf in the sub-scanning direction is larger than the size Ls in the main scanning direction, even if the image areas are the same, the time required for forming the image patterns 31A and 31B, that is, the productivity, is different. For example, assuming that the size Ls in the main scanning direction of the irradiation region 21A in Fig. 10(a) is 50.8 [mm] and the size Lf in the sub-scanning direction is 25.4 [mm], and the size Ls in the main scanning direction of the irradiation region 21B in Fig. 10(b) is 25.4 [mm] and the size Lf in the sub-scanning direction is 50.8 [mm], and using the above formula (2) to calculate the time ta [s] required for forming the image patterns 31A and 31B respectively, in the case of Fig. 10(a), ta [s] = 0.20, while in the case of Fig. 10(b), ta [s] = 0.30.

[0075] Thus, for the same area (50.8 [mm] × 25.4 [mm] = 1290 [mm 2) Even when forming the image patterns 31A and 31B in the irradiation regions 21A and 21B, when laser irradiation is performed with the direction along the conveyance direction F as the main scanning direction, the irradiation region 21A with a larger main scanning direction size Ls requires a shorter time ta for forming the image pattern than the irradiation region 21B with a larger sub-scanning direction size Lf. This is presumably because when the main scanning direction size Ls is large, the number of times of reverse scanning of the laser decreases, and thus the time required for forming the image pattern becomes shorter.

[0076] From the above, in the present invention, a laser irradiation device, a laser irradiation system, and a laser irradiation method are proposed in which the laser is scanned so that the main scanning direction is along the conveyance direction F with respect to the irradiation region 21A where the main scanning direction size Ls is equal to or greater than the sub-scanning direction size Lf. Thereby, it is possible to improve the laser irradiation accuracy with respect to the container being conveyed and also to improve productivity.

[0077] Subsequently, another embodiment of the present invention will be described. Hereinafter, the parts different from the first embodiment of the present invention will be mainly described, and the same parts will be omitted as appropriate.

[0078] <Second Embodiment of the Present Invention> As described above, in the first embodiment of the present invention, one of the characteristic parts is that, in order to improve productivity, the laser is irradiated to the irradiation region where the size in the main scanning direction is equal to or greater than the size in the sub-scanning direction. However, depending on the design of the image pattern or the like, there may be a case where an image pattern 31B that is large in the sub-scanning direction as shown in FIG. 10(b) is required.

[0079] Therefore, in the second embodiment of the present invention, even when a large image pattern 31B in the sub-scanning direction is required, in order to improve productivity, as shown in FIG. 11, the irradiation area 21 is divided into a plurality of irradiation areas 21a to 21d extending in the sub-scanning direction (the vertical direction in the figure), and laser irradiation is performed individually on each of the irradiation areas 21a to 21d. Thus, by dividing the irradiation area 21 into a plurality of irradiation areas 21a to 21d, the size Lf of each irradiation area 21a to 21d in the sub-scanning direction can be reduced, and therefore the laser irradiation time for each irradiation area 21a to 21d can be shortened.

[0080] FIG. 12 is a plan view of a laser irradiation system according to the second embodiment of the present invention.

[0081] As shown in FIG. 12, in the laser irradiation system 1000 according to the second embodiment of the present invention, the laser irradiation device 100 includes a plurality of scanning means 13. Also, corresponding to the number of the scanning means 13, a plurality of laser oscillation sources 11, optical systems 12, and condensing means 14 are respectively provided. Here, only the first galvanometer mirror 15 is shown as the scanning means 13, but each of the scanning means 13 is configured to be able to two-dimensionally scan a laser using two galvanometer mirrors.

[0082] In the second embodiment of the present invention, when the container 1 is conveyed from left to right in FIG. 12, the container 1 sequentially passes through a plurality of laser irradiation areas U1 to U4. When the container 1 reaches the first laser irradiation area U1, the irradiation area 21a of the container 1 is irradiated with the laser L. Next, when the container 1 reaches the second laser irradiation area U2, another irradiation area 21b on the container 1 is irradiated with the laser L. Thereafter, in the same manner, each time the container 1 reaches the third laser irradiation area U3 and the fourth laser irradiation area U4, the different irradiation areas 21c and 21d are individually irradiated with the laser L.

[0083] Thus, in the case of the second embodiment of the present invention, even when the laser L is scanned so that the direction along the conveyance direction F becomes the main scanning direction by irradiating the plurality of irradiation regions 21a to 21d individually, the laser irradiation time in each of the irradiation regions 21a to 21d can be shortened. Therefore, productivity is improved.

[0084] As described above, in the second embodiment of the present invention, even for a large image pattern 31B in the sub-scanning direction, the irradiation region 21 is divided into a plurality of irradiation regions 21a to 21d across the sub-scanning direction, and the laser is irradiated to each of the irradiation regions 21a to 21d individually, so that an image pattern can be formed in a short time and productivity can be improved.

[0085] Note that the order of laser irradiation for each of the irradiation regions 21a to 21d may be from the uppermost irradiation region 21a shown in FIG. 11 or from the lowermost irradiation region 21d. Further, the number of divided irradiation regions may be two or three, or five or more in addition to the four cases as shown in FIG. 11.

[0086] <The Third Embodiment of the Present Invention> FIG. 13 is a plan view of a laser irradiation system according to the third embodiment of the present invention.

[0087] The third embodiment of the present invention is a configuration in which, in the second embodiment of the present invention, the scanning ranges of the plurality of scanning means 13 are set to overlap each other.

[0088] In this case, as in the second embodiment of the present invention, since the laser is irradiated to the plurality of irradiation regions 21a to 21d divided across the sub-scanning direction individually, productivity can be improved. Further, in this case, the installation space of the laser irradiation device 100 can be made space-saving. Also, the time required for forming the image pattern can be shortened.

[0089] <The Fourth Embodiment of the Present Invention> Subsequently, the fourth embodiment of the present invention will be described.

[0090] In a container with unevenness on its surface such as a PET bottle, when an image pattern is formed on the uneven portion of the container, the visibility of the image pattern may decrease or it may become difficult to distinguish the image pattern. For this reason, if possible, it is preferable to form the image pattern avoiding the uneven portion. However, as shown in FIGS. 14(a) to (c), depending on the container 1, there are those in which the height dimension H varies greatly. In this case, since the position of the uneven portion 3 varies as the height dimension H of the container 1 varies, even if the irradiation region 21 is set at the same height, the relative position of the irradiation region 21 with respect to the uneven portion 3 is different. As a result, originally, as shown in FIG. 15(a), where the image pattern 31 should be formed between the uneven portions 3, the image pattern 31 may be formed so as to overlap the uneven portion 3 as shown in FIG. 15(b) (see the image pattern 31 of "numbers" on the lower side in FIG. 15(b)).

[0091] Therefore, in the fourth embodiment of the present invention, in order to prevent the image pattern 31 from overlapping the uneven portion 3 of the container 1, the following configuration is adopted.

[0092] FIG. 16 is a plan view of a laser irradiation system according to the fourth embodiment of the present invention.

[0093] In the fourth embodiment of the present invention shown in FIG. 16, the laser irradiation device 100 includes unevenness detection means 18 for detecting the position of the uneven portion on the surface of the container 1. Here, the "uneven portion" means a convex portion, a concave portion, or a concept including both of them. The unevenness detection means 18 can be appropriately selected as long as it can detect the position of the uneven portion on the surface of the container 1. In this case, as an example of the unevenness detection means 18, a camera 8 for imaging the surface of the container 1 is used.

[0094] The unevenness detection means 18 is arranged on the upstream side in the conveyance direction F from the laser irradiation area U. For this reason, when the container 1 is conveyed along the conveyance path 20, before the container 1 reaches the laser irradiation area U, the position of the uneven part of the container 1 is detected by the unevenness detection means 18. Further, the position information of the uneven part detected by the unevenness detection means 18 is sent from the unevenness detection means 18 to the control unit 400. Then, the control unit 400 controls the scanning means 13 based on the detection result of the unevenness detection means 18, and scans the laser so that the laser is irradiated to an irradiation area that does not overlap with the uneven part.

[0095] As described above, in the fourth embodiment of the present invention, based on the detection result of the unevenness detection means 18, the laser is irradiated so as not to overlap with the uneven part of the container 1, so that, as shown in FIG. 17, the image pattern 31 can be formed while avoiding the uneven part 3. Thereby, the visibility and discriminability of the image pattern 31 can be ensured well.

[0096] <The Fifth Embodiment of the Present Invention> Subsequently, the fifth embodiment of the present invention will be described.

[0097] When the surface of the container 1 is irradiated with a laser and the properties of the surface of the container change, fine particles called fumes may be generated as dust. And when such fine particles exist on the laser irradiation path (scanning range), the laser is diffusely reflected by the particles, so that the desired laser energy does not reach the surface of the container, and there is a risk of processing defects. Therefore, it is preferable to move the fine particles from the laser irradiation path (scanning range) using an air flow generating means such as a fan.

[0098] Therefore, in the fifth embodiment of the present invention, as shown in FIG. 11, when irradiating a plurality of irradiation areas 21a to 21d arranged in the vertical direction with a laser, the irradiation order of the laser and the generation direction of the air flow are set as follows.

[0099] Figures 18(a) to 18(d) are diagrams showing the laser irradiation order for a plurality of irradiation regions 21a to 21d and the direction of airflow generation in the fifth embodiment of the present invention.

[0100] In the laser irradiation apparatus 100 according to the fifth embodiment of the present invention, an airflow generation means 19 for generating an airflow is provided. Here, an intake device 7 is used as the airflow generation means 19, but the airflow generation means 19 may be a blower device such as a fan or a circulator in addition to the intake device 7.

[0101] The intake device 7 is arranged so as to be positioned below the container 1 to be conveyed. Therefore, when the surrounding air is sucked by the intake device 7, an airflow is generated from above to below along the surface of the container 1 (while contacting the surface). Further, it is preferable that a part of the air supply port of the intake device 7 is arranged so as to overlap the container 1 (enter inside the surface of the container 1) when viewed from above the container 1 so that an airflow is generated along the surface of the container 1.

[0102] Also, the laser is scanned so as to be irradiated in order from the lowermost irradiation region 21d. Therefore, when the container 1 reaches the first laser irradiation area, first, as shown in FIG. 18(a), the lowermost irradiation region 21d is irradiated with the laser, and the image pattern 31 (image line 30) is formed. At this time, dust 50 containing fine particles is generated by the laser irradiation. However, on the surface of the container 1, an airflow is generated from above to below by the intake device 7, so the dust 50 moves downward. As a result, since the upward movement of the dust 50 is suppressed, it is possible to avoid the laser irradiation being affected by the dust 50 when the laser irradiates the next upper irradiation region 21c (in the case of FIG. 18(b)).

[0103] Subsequently, even when the laser is irradiated onto the irradiation region 21c one above, dust 50 is generated. Also in this case, since the dust 50 moves downward by the suction of the intake device 7, even when the laser is irradiated onto the irradiation region 21c one above (in the case of FIG. 18(c)), it is possible to avoid the laser irradiation being affected by the dust 50. Similarly, also in the irradiation regions 21b and 21a to be subsequently laser-irradiated, since the generated dust 50 moves downward, it is possible to avoid the influence of the dust 50 on the laser irradiation.

[0104] Thus, in the fifth embodiment of the present invention, by performing the laser irradiation in order from the lowermost irradiation region 21d and setting the direction of the airflow generated at that time to be from above downward, it is possible to avoid the influence of the dust 50 on the laser irradiation and to form a good image pattern.

[0105] Also, the order of laser irradiation may be from the uppermost irradiation region 21a instead of from the lowermost irradiation region 21d. In that case, also by setting the direction of the airflow to be from below upward, conversely, it is possible to avoid the dust 50 generated in the upper irradiation region from affecting the laser irradiation in the lower irradiation region. Therefore, the direction of generation of the airflow may be made different according to the order of laser irradiation. However, since the particles contained in the dust 50 have mass even if they are fine, it is effective in promoting the movement of the dust 50 to generate an airflow downward in the direction of gravity. Therefore, in order to more effectively avoid the influence of the dust 50, it is preferable to irradiate the laser in order from the lowermost irradiation region 21d as in the fifth embodiment of the present invention and to generate the airflow downward.

[0106] <Relationship between the deviation amount in the optical axis direction of the laser irradiation position and the depth of focus> Subsequently, the relationship between the deviation amount D in the optical axis direction of the laser irradiation position on the container and the depth of focus DOF of the laser will be described when the container is conveyed along a curved conveyance path.

[0107] FIG. 19 is a plan view of an annular conveyance path 20 as viewed from a direction orthogonal to the plane including the conveyance path circle. FIG. 20 is a plan view showing the container 1 on a part of the conveyance path 20 in FIG. 19.

[0108] As shown in FIG. 19, when the container 1 is conveyed from left to right in the figure along the annular conveyance path 20, first, laser irradiation on the container 1 is started at a position (z1) on the conveyance path 20. Subsequently, the container 1 passes through a position (z2) on the conveyance path 20, and the laser irradiation on the container 1 ends at a position (z3) on the conveyance path 20. At this time, the container 1 is conveyed so as to approach the laser irradiation device 100 from the irradiation start position (z1) where the laser irradiation is started to the intermediate position (z2) of the laser irradiation area U, and then, from the intermediate position (z2) to the irradiation end position (z3) where the laser irradiation ends, it is conveyed so as to move away from the laser irradiation device 100. In FIG. 19, a point (a) on the container 1 is the laser irradiation start point on the container 1 at the irradiation start position (z1), and a point (b) is the laser irradiation end point on the container 1 at the irradiation end position (z3).

[0109] Here, when the straight line direction passing through the center O of the conveyance path circle along the conveyance path 20 and the front position (c) of the container 1 when the container 1 is closest to the laser emission reference point Q (in this case, when the container 1 is closest to the laser emission point of the second galvanometer mirror 16) is defined as the "Y-axis direction", the laser irradiation position on the container 1 is displaced by a distance D in the Y-axis direction in FIG. 19 as the container 1 moves. That is, when the container 1 is conveyed along the annular conveyance path 20, the laser irradiation position on the container 1 changes by a distance D in the Y-axis direction between the irradiation start position (z1) and the irradiation end position (z3). On the other hand, there is an effective focal range in the laser irradiation device 100 that can effectively irradiate the object with laser light.

[0110] FIG. 21 is a graph showing the relationship between the distance from the best focus position of the focal range to the laser irradiation position and the beam diameter of the laser.

[0111] When a laser is focused by a lens, the relationship between the beam diameter and the distance from the best focus position to the laser irradiation position generally forms a parabola. As shown in FIG. 21, when the distance from the best focus position to the laser focus position increases significantly in the positive or negative direction, the beam diameter gradually increases, which is disadvantageous for performing accurate laser irradiation. Therefore, in order to perform accurate laser irradiation, it is preferable that the displacement amount D of the laser irradiation position in the Y-axis direction is within the effective focus range (2DoF).

[0112] Here, in FIG. 19, when laser irradiation is started on the container 1, let the center position of the container 1 be P1, the center of the transport path circle be O, and when the container 1 is closest to the laser emission reference point Q, let the center position of the container 1 be P2, and the angle P1 - O - P2 be θ1. Also, in FIG. 20, let the central angle of the arc region (irradiation region 21) on the surface of the container 1 where the laser is irradiated be θ2, the radius of the transport path circle be R, and the radius of the cylindrical surface of the container 1 be r. Then, the distances y1, y2, and y3 in the Y-axis direction in FIG. 20 are expressed as follows in the following formulas (3), (4), and (5). The distance y1 is the distance in the Y-axis direction between the center O of the transport path circle and the center P1 of the container 1 at the irradiation start position (z1). Also, the distance y2 is the distance in the Y-axis direction between the center P1 of the container 1 at the irradiation start position (z1) and the laser irradiation start point (a) on the container 1 at the irradiation start position (z1). Also, the distance y3 is the distance in the Y-axis direction between the center O of the transport path circle and the front position (c) of the container 1 when the container 1 is closest to the laser emission reference point Q (intermediate position (z2)).

[0113]

Equation

[0114]

Equation

[0115]

Equation

[0116] Then, using the above formulas (3), (4), and (5), the displacement amount D of the laser irradiation position in the Y-axis direction is expressed as the following formula (6).

[0117]

Equation

[0118] In this case, the container 1 moves along a symmetric path from the irradiation start position (z1) to the irradiation end position (z3) with the intermediate position (z2) closest to the laser emission reference point Q in between. Therefore, the displacement amount D of the laser irradiation position in the Y-axis direction from the irradiation start position (z1) to the intermediate position (z2) is the same as the displacement amount D of the laser irradiation position in the Y-axis direction from the intermediate position (z2) to the irradiation end position (z3). Accordingly, in FIG. 20, the distance in the Y-axis direction between the laser irradiation positions at the irradiation start position (z1) and the intermediate position (z2) is taken as the displacement amount D of the laser irradiation position in the Y-axis direction.

[0119] Also, assuming that the maximum distance from the best focus position N of the laser shown in FIG. 20 to the effective focus position is the focus depth DoF, the effective focus range can be expressed as 2DoF, which is twice the DoF. Therefore, in order to perform laser irradiation with high accuracy, it is preferable to satisfy the following relationship of formula (7) so that the displacement amount D of the laser irradiation position in the Y-axis direction is within the effective focus range (2DoF). The best focus position N is on the side of the center O of the transport path circle rather than the front position (c) of the container 1 when the container 1 is closest to the laser emission reference point Q.

[0120]

Equation

[0121] In this way, by setting various parameters so that the displacement amount D of the laser irradiation position in the Y-axis direction falls within the effective focal range (2DoF), the laser irradiation accuracy can be improved.

[0122] Here, the parameters used in laser processing are defined by the beam spot diameter during laser irradiation and the elements indicating the performance and configuration of the laser irradiation device used in the following formulas (8) and (9). The pulse width represents the time during which one pulse of the laser irradiates the object. In the order of nanoseconds, processing is performed by thermal denaturation according to the absorption spectrum of the object, and in the order of picoseconds or less, in addition to thermal denaturation, a phenomenon occurs in which the states of electrons and atoms transition to high energy levels due to the absorption of multiple photons simultaneously, called multiphoton absorption, which is the absorption of 1 / 2 to 1 / 3 of the wavelength of the used laser wavelength. As a result, the solid material is sublimated without going through a molten state, and processing marks can be obtained.

[0123]

Number

[0124]

Number

[0125] In the above formula (8), P is the average output [W] of the pulsed laser, E is the pulse energy [J], and ν is the repetition frequency [Hz] of the pulsed laser. Also, in the above formula (9), F is the fluence [J / cm 2 , and S is the area [cm 2 of the laser beam spot diameter. The energy E per pulse is the value obtained by dividing the average output by the repetition frequency ν, and the fluence F is the value obtained by dividing the energy E per pulse by the area S of the laser beam spot diameter.

[0126] In the embodiment of the present invention, IceFyre 355-50 manufactured by Spectra-Physics (wavelength: 355 [nm], pulse width: 10 [ps]) was used, and the processing accuracy by laser irradiation was evaluated under the conditions of 50 [W], 1000 [kHz], and fθ lens focal length: f580. As a result, at a beam waist diameter of 73 [μm], from the best focus position to a depth of focus DoF of 12 [mm], the processing quality by laser irradiation was in a good state.

[0127] FIG. 22 is a plan view showing another conveyance mode of the storage container 1 conveyed along the annular conveyance path 20.

[0128] In FIG. 22, the storage container 1 is conveyed such that the middle position (m) in the width direction of the irradiation region 21 is always directly facing a plane orthogonal to the laser optical axis (Y-axis direction), which is different from the examples shown in FIGS. 19 and 20. That is, in FIGS. 19 and 20, the middle position (m) in the width direction of the irradiation region 21 is conveyed so as to face the outside in the radial direction of the conveyance path circle, but in FIG. 22, the storage container 1 is conveyed on the conveyance path 20 while rotating, so that the middle position (m) in the width direction of the irradiation region 21 is always directly facing a plane orthogonal to the laser optical axis. Otherwise, it is the same as the examples in FIGS. 19 and 20.

[0129] In this case, the distances y1, y2, y3 in the Y-axis direction in FIG. 22 are expressed as in the following formulas (10), (12), (12). Here, the distances y1, y2, y3, and θ1, θ2, r, R in each formula are the same values as the distances y1, y2, y3 and θ1, θ2, r, R in formulas (3), (4), (5) in FIG. 20 above.

[0130]

Equation

[0131]

Equation

[0132] [Number]

[0133] Also, by using the above formulas (10), (11), and (12), the displacement amount D of the laser irradiation position in the Y-axis direction here is expressed as the following formula (13).

[0134] [Number]

[0135] Therefore, also in this case, in order to perform laser irradiation with high accuracy, it is preferable that the displacement amount D of the laser irradiation position in the Y-axis direction satisfies the following relationship (14) so as to be within the effective focal range (2DoF). As a result, the laser irradiation accuracy can be improved.

[0136] [Number]

[0137] Also, in the example shown in FIG. 20 or FIG. 21, the intermediate position Dm in the Y-axis direction between the laser irradiation start point (a) on the container 1 at the irradiation start position (z1) and the front position (c) of the container 1 when the container 1 is closest to the laser emission reference point Q (intermediate position (z2)) is preferably the best focus position N. As a result, when the container 1 is conveyed along the annular conveyance path 20, the irradiation region 21 of the container 1 is likely to be included within the effective focal range (2DoF), so that the laser irradiation accuracy can be improved.

[0138] Note that the relationship between the deviation amount (displacement amount D of the laser irradiation position) in the optical axis direction of the laser irradiation position and the depth of focus (DoF) as described above is not limited to the case where the container 1 is conveyed along the annular conveyance path 20, but is also applicable when the container 1 is conveyed along a curvilinear conveyance path 20 other than annular.

[0139] <Regarding the Laser Emission Reference Position> FIG. 23 is a diagram showing a preferable laser emission reference position Q.

[0140] As shown in FIG. 23, when viewed from a direction orthogonal to the plane including the conveyance path circle, the laser emission reference point Q is preferably arranged on a straight line M passing through the center position P2 of the container 1 when the container 1 is closest to the laser emission reference point Q and the center O of the conveyance path circle. In this way, by arranging the laser emission reference point Q on the straight line M, laser irradiation can be accurately performed in a short time over a wide range in the conveyance direction F.

[0141] Note that the laser emission reference point Q is not necessarily limited to being arranged on the straight line M, and it may be arranged at a position deviated from the straight line M. However, in order to improve the laser irradiation accuracy, it is preferable that the deviation amount β of the laser emission reference point Q with respect to the straight line M shown in FIG. 23 is less than ±5°. This deviation amount β of the laser emission reference point Q is the deviation amount in the circumferential direction centered on the center position P2 of the container 1 when the container 1 is closest to the laser emission reference point QQ with respect to the straight line M. In this way, by arranging the laser emission reference point Q within a range of less than ±5° in the circumferential direction centered on the center position P2 of the container 1 when the container 1 is closest to the laser emission reference point Q with respect to the straight line M, the laser irradiation accuracy can be improved.

[0142] <Regarding the Characteristic Portion of the Image Pattern (Modified Portion) Formed Using the Present Invention> FIGS. 24(a) to (e) are diagrams showing examples of image patterns formed using the present invention.

[0143] In the present invention, since the laser is scanned so that the main scanning direction of the laser is along the conveyance direction F, as shown in FIGS. 24(a) to (d), an image pattern 31 in which a plurality of modified portions 2 are arranged in the conveyance direction F is formed. Further, when a continuous laser (CW laser) oscillation source is used as the laser oscillation source, a linear image pattern 31 continuously extending in the conveyance direction F as shown in FIG. 24(e) is formed.

[0144] Here, when the laser oscillation source is a pulse laser oscillation source, since the laser is irradiated at a predetermined frequency while being scanned in the conveyance direction F, basically, as shown in FIGS. 24(a) or (c), the intervals Pm between a plurality of modified portions 2 arranged in the conveyance direction F are equal. However, when vibrations or speed fluctuations occur in the container during conveyance, the laser irradiation is affected by the vibrations or speed fluctuations, and variations may occur in the intervals Pm between adjacent modified portions 2 as shown in FIGS. 24(b) or (d). However, in the case of the present invention, as described above, it is possible to reduce the variations in the intervals Pm between the modified portions 2 as compared with the comparative example in which the laser is scanned in a direction intersecting the conveyance direction F.

[0145] FIG. 25(a) shows an image pattern 31 formed using the present invention, and FIG. 25(b) shows an image pattern 31 formed using a comparative example.

[0146] As shown in FIG. 25(a), in the case of the present invention, since the laser scanning in the direction along the conveyance direction F (main scanning direction) is repeated in the direction intersecting the conveyance direction F (sub-scanning direction), a plurality of image lines 30 extending in the conveyance direction F are formed so as to be arranged in the direction intersecting the conveyance direction F.

[0147] On the other hand, in the case of the comparative example of FIG. 25(b), since the laser scanning in the direction intersecting the conveyance direction F is repeated across the conveyance direction F, a plurality of image lines 30 extending in the direction intersecting the conveyance direction F are formed so as to be arranged in the conveyance direction F.

[0148] Here, when forming an image line 30 as shown in FIG. 25(a) in the present invention, if vibrations or speed fluctuations occur in the conveyance direction F, as shown in FIG. 26(a), a portion K where the interval Pm between the modified portions 2 increases due to the vibrations or speed fluctuations occurs for each image line 30. In this case, usually, since the timing at which the vibrations or speed fluctuations occur is different for each image line 30, the position of the portion K where the interval Pm between the modified portions 2 increases is also basically different for each image line 30.

[0149] On the other hand, in the case of the comparative example, since the image lines 30 extending in a direction intersecting the conveyance direction F are formed to be arranged in a plurality in the conveyance direction F, when vibration or speed variation occurs in the conveyance direction F, as shown in FIG. 26(b), a portion K where the interval between the image lines 30 becomes large is generated between the image lines 30. In this case, the portion K where the interval becomes large is continuously generated in a direction intersecting the conveyance direction F.

[0150] As described above, in the present invention and the comparative example, the position and the generation mode of the portion where the interval between the modified portions becomes large due to vibration or speed variation are different. In particular, in the case of the present invention, compared with the comparative example, the position of the portion K where the interval becomes large tends to vary for each image line 30 across the conveyance direction F. Therefore, whether it is an image pattern formed by the present invention or an image pattern formed by the comparative example can be determined as follows based on the position and the generation mode of the portion where the interval between the modified portions becomes large.

[0151] For example, as shown in FIG. 27, in the image pattern 31 formed by the present invention, when the portion where the interval between adjacent modified portions 2 on each image line 30 is the largest is referred to as the maximum interval portion Kmax, the number of combinations of the image lines 30 having different positions (maximum interval positions) of the maximum interval portion Kmax is likely to be more than half of the total number of all the image lines 30.

[0152] As shown in FIG. 27, when six image lines 30 extending in the conveyance direction F (main scanning direction) are arranged in a direction (sub-scanning direction) intersecting the conveyance direction F, since the mutually different maximum gap positions are at three locations K1, K2, and K3 across the conveyance direction F, the number of combinations of the image lines 30 having different maximum gap positions is three, namely, K1-K2, K2-K3, and K1-K3. In this case, since the total number of all the image lines 30 is six, the number of combinations of the image lines 30 having different maximum gap positions (three) is more than half of the total number of all the image lines 30 (six).

[0153] On the other hand, as shown in FIG. 28, when the number of combinations of the image lines 30 with different maximum gap positions is only one of K1 - K2, the number of combinations (one) of the image lines 30 with different maximum gap positions does not exceed half of the number of all the image lines 30 (six).

[0154] Also, as in the comparative example of FIG. 26(b), when the portions K where the intervals become large continuously occur in a direction intersecting the conveyance direction F, as shown in FIG. 29, when regarded as the image lines 30 extending in the conveyance direction F, the maximum interval positions on each image line 30 are the same as each other. In this case, since the number of combinations of the image lines 30 with different maximum interval positions across the conveyance direction F becomes zero, in the case of the comparative example, the number of combinations (zero) of the image lines 30 with different maximum gap positions does not exceed half of the number of all the image lines 30 (six).

[0155] Therefore, by checking whether the number of combinations of the image lines 30 with different maximum gap positions exceeds half of the number of all the image lines 30, it is possible to discriminate whether the image pattern is obtained by the present invention or the image pattern obtained by the comparative example.

[0156] Note that in FIG. 27, the number of the image lines 30 extending in the conveyance direction F is six, but the above determination method is not limited to the case where the number of the image lines 30 is six. The determination as to whether it is the image pattern of the present invention can be made if, as shown in FIG. 30, there is a region where at least three or more image lines 30 in which the modified portions 2 are arranged continuously in the conveyance direction F are formed in two or more rows in a direction intersecting the conveyance direction F.

[0157] Summarizing the aspects of the present invention described above, the present invention includes at least the following aspects.

[0158] [First Aspect] The first aspect is a laser irradiation device that irradiates a laser to an irradiation region of a workpiece to be conveyed, including a laser oscillation source that oscillates the laser, and scanning means that two-dimensionally scans the laser oscillated from the laser oscillation source in scanning directions intersecting each other in the irradiation region. Comprising, among the mutually intersecting scanning directions, the direction with a longer scanning distance in one scan as the main scanning direction, and the direction intersecting with the main scanning direction as the sub-scanning direction, when the scanning means scans the laser beam so that the size in the main scanning direction is equal to or greater than the size in the sub-scanning direction of the irradiation region, the main scanning direction is along the conveyance direction of the workpiece. It is a laser irradiation device that scans the laser beam.

[0159] [Second Aspect] The second aspect is, in the first aspect, provided with a plurality of scanning means for scanning the laser beam so that the laser beam is irradiated to the respective different irradiation regions, and the plurality of scanning means each have a size in the main scanning direction equal to or greater than the size in the sub-scanning direction. For the irradiation region, the laser beam is scanned so that the main scanning direction is along the conveyance direction of the workpiece.

[0160] [Third Aspect] The third aspect is, in the first or second aspect, provided with unevenness detection means for detecting the position of convex portions or concave portions on the surface of the workpiece, and the scanning means is based on the detection result of the unevenness detection means. The laser beam is scanned so that the laser beam is irradiated to the irradiation region that does not overlap with the convex portion or the concave portion.

[0161] [Fourth Aspect] The fourth aspect is, in any one of the first to third aspects, provided with airflow generation means for generating an airflow on the surface of the workpiece, and the scanning means irradiates the laser beam in order to a plurality of the irradiation regions arranged in the vertical direction on the surface of the workpiece. The laser beam is scanned so that the laser beam is irradiated, and the airflow generation means varies the direction of the airflow according to the order in which the laser beam is irradiated to the irradiation region. The laser irradiation device according to claim 1.

[0162] [Fifth Aspect] The fifth aspect is, in the fourth aspect, the scanning means scans the laser beam so that the laser beam is irradiated in order from the lowermost irradiation region, and the airflow generation means generates an airflow from above to below.

[0163] [Aspect 6] Aspect 6 is a laser irradiation device that irradiates a laser onto the cylindrical surface of the workpiece being conveyed along a curved conveyance path in any one of the first to fifth aspects. When the center position of the workpiece when laser irradiation is started on the workpiece is defined as P1, the center of the conveyance path circle along the curved conveyance path is defined as O, and the center position of the workpiece when the workpiece is closest to the laser emission reference point is defined as P2, the angle P1 - O - P2 is defined as θ1, the central angle of the arc region on the surface of the workpiece where the laser is irradiated is defined as θ2, the radius of the conveyance path circle is defined as R, the radius of the cylindrical surface of the workpiece is defined as r, and the depth of focus of the laser is defined as DoF, the relationship R(1 - cosθ1)+r(1 - cos(θ1 + θ2 / 2)) < 2×DoF is satisfied, and the best focus position of the laser is on the center side of the conveyance path circle rather than the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point.

[0164] [Aspect 7] The seventh aspect is as follows. In any one of the first to fifth aspects, on the conveying path on the curve, the laser is irradiated onto the surface of the workpiece to form an image pattern such that the mid-position in the width direction of the arc region on the cylindrical surface of the workpiece, which is irradiated with the laser, faces a plane orthogonal to the laser optical axis. When the central position of the workpiece at the start of laser irradiation on the workpiece is P1, the center of the conveying path circle along the curved conveying path is O, and the central position of the workpiece when the workpiece is closest to the laser emission reference point is P2, the angle P1 - O - P2 is θ1. When the central angle of the arc region on the surface of the workpiece, which is irradiated with the laser, is θ2, the radius of the conveying path circle is R, the radius of the cylindrical surface of the workpiece is r, and the depth of focus of the laser is DoF, the relationship R(1 - cosθ1)+r(1 - cos(θ2 / 2)) < 2×DoF is satisfied, and the best focus position of the laser is on the center side of the curved conveying path rather than the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point.

[0165] [Eighth Aspect] The eighth aspect is as follows. In any one of the first to seventh aspects, it is a laser irradiation device that irradiates a laser onto the surface of the workpiece conveyed along a curved conveying path. When the straight line direction passing through the center of the conveying path circle and the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point is defined as the Y-axis direction when viewed from a direction orthogonal to the plane including the conveying path circle along the curved conveying path, the intermediate position in the Y-axis direction between the laser irradiation start point of the workpiece at the start of laser irradiation on the workpiece and the front position of the workpiece when the workpiece is closest to the laser emission reference point is set to be the best focus position of the laser.

[0166] [Ninth Aspect] Aspect 9 is a laser irradiation device that irradiates a laser onto the surface of the workpiece being conveyed along a curved conveyance path. When viewed from a direction orthogonal to the plane including the conveyance path circle along the curved conveyance path, the laser emission reference point is arranged on a straight line passing through the center position of the workpiece when the workpiece is closest to the laser emission reference point and the center of the conveyance path circle.

[0167] [Aspect 10] Aspect 10 is a laser irradiation device that irradiates a laser onto the surface of the workpiece being conveyed along a curved conveyance path. When viewed from a direction orthogonal to the plane including the conveyance path circle along the curved conveyance path, the laser emission reference point is arranged within a range of less than ±5° in the circumferential direction centered on the center position of the workpiece when the workpiece is closest to the laser emission reference point, with reference to the straight line passing through the center position of the workpiece when the workpiece is closest to the laser emission reference point and the center of the conveyance path circle.

[0168] [Aspect 11] Aspect 11 is a laser irradiation method for irradiating a laser onto an irradiation area of a workpiece being conveyed. When two-dimensionally scanning the laser in scanning directions intersecting each other on the surface of the workpiece, among the intersecting scanning directions, when the direction with a longer scanning distance in one scan is defined as the main scanning direction and the direction intersecting the main scanning direction is defined as the sub-scanning direction, the laser is scanned so that the main scanning direction is along the conveyance direction of the workpiece for the irradiation area where the size in the main scanning direction is equal to or greater than the size in the sub-scanning direction.

[0169] [Aspect 12] The twelfth aspect is a laser irradiation system including a conveying means for conveying a workpiece and a laser irradiation device for irradiating a surface of the workpiece to be conveyed with a laser to form an image pattern. The laser irradiation device includes a laser oscillation source for oscillating the laser and a scanning means for two-dimensionally scanning the laser oscillated from the laser oscillation source in scanning directions intersecting each other on the surface of the workpiece. Among the scanning directions intersecting each other, when a direction in which the scanning distance is long in one scan is defined as a main scanning direction and a direction intersecting the main scanning direction is defined as a sub-scanning direction, the scanning means scans the laser so that the main scanning direction is along the conveying direction of the workpiece with respect to the irradiation region in which the size in the main scanning direction is equal to or larger than the size in the sub-scanning direction.

[0170] [Aspect 13] The thirteenth aspect is a workpiece in which a modified portion is formed on the surface by the laser irradiation method of the eleventh aspect, and the modified portions are formed so as to be continuously arranged along the conveying direction of the workpiece conveyed during laser irradiation.

[0171] [Aspect 14] The fourteenth aspect is the aspect of the thirteenth aspect, in a region where at least three or more image lines in which the modified portions are continuously arranged along the conveying direction of the workpiece are formed in two or more rows in a direction intersecting the conveying direction, there is a portion where the interval between adjacent modified portions on each of the image lines is the largest, and the number of combinations of the image lines in which the maximum gap positions where the intervals are the largest are different from each other is more than half of the total number of the image lines.

Explanation of Reference Numerals

[0172] 1 Container (Workpiece) 2 Modified Portion 11 Laser Oscillation Source 13 Scanning Means 18 Concavo-Convex Detection Means 19 Airflow Generation Means 21 Irradiation Region 31 Image Pattern 100 Laser irradiation device 200 Conveying means 1000 Laser irradiation system F Conveying direction

Prior art documents

Patent documents

[0173]

Patent Document 1

Claims

1. A laser irradiation device that irradiates a laser to an irradiation region of a workpiece to be conveyed, comprising: a laser oscillation source that oscillates the laser; scanning means for two-dimensionally scanning the laser oscillated from the laser oscillation source in scanning directions that intersect each other in the irradiation region; and is provided with Among the scanning directions that intersect each other, when the direction with a longer scanning distance in one scan is defined as the main scanning direction and the direction intersecting the main scanning direction is defined as the sub-scanning direction, the scanning means scans the laser so that the main scanning direction is along the conveyance direction of the workpiece with respect to the irradiation region where the size in the main scanning direction is equal to or greater than the size in the sub-scanning direction. A laser irradiation device characterized by this.

2. Comprising a plurality of scanning means for scanning the laser so that the laser is irradiated to each different irradiation region, The plurality of scanning means scan the laser so that the main scanning direction is along the conveyance direction of the workpiece with respect to the irradiation region where the size in the main scanning direction is equal to or greater than the size in the sub-scanning direction for each. The laser irradiation device according to claim 1.

3. Comprising unevenness detection means for detecting the position of a convex portion or a concave portion on the surface of the workpiece, The scanning means scans the laser so that the laser is irradiated to the irradiation region that does not overlap with the convex portion or the concave portion based on the detection result of the unevenness detection means. The laser irradiation device according to claim 1.

4. Comprising airflow generation means for generating an airflow on the surface of the workpiece, The scanning means scans the laser so that the laser is sequentially irradiated to a plurality of the irradiation regions arranged in the vertical direction on the surface of the workpiece, The airflow generation means varies the direction of the airflow according to the order in which the laser is irradiated to the irradiation region. The laser irradiation device according to claim 1.

5. The scanning means scans the laser so that the laser is irradiated in order from the lowermost irradiation region, The airflow generation means generates an airflow from above to below. The laser irradiation device according to claim 4.

6. A laser irradiation device that irradiates a laser to the cylindrical surface of a workpiece conveyed along a curved conveyance path, comprising: Let the center position of the workpiece when laser irradiation is started to the workpiece be P1, Let the center of the conveyance path circle along the curved conveyance path be O, When the center position of the workpiece when it is closest to the laser emission reference point is defined as P2, let the angle P1 - O - P2 be θ1, let the central angle of the arc region on the surface of the workpiece where the laser is irradiated be θ2, let the radius of the transport path circle be R, let the radius of the cylindrical surface of the workpiece be r, when the depth of focus of the laser is DoF, the relationship R(1 - cosθ1) + r(1 - cos(θ1 + θ2 / 2)) < 2×DoF is satisfied, The best focus position of the laser is on the center side of the transport path circle rather than the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point. The laser irradiation device according to claim 1.

7. A laser irradiation device that irradiates the surface of the workpiece transported on a transport path on a curve so that the widthwise intermediate position of the arc region on the cylindrical surface of the workpiece where the laser is irradiated faces a plane orthogonal to the laser optical axis, when the center position of the workpiece when laser irradiation starts on the workpiece is defined as P1, let the center of the transport path circle along the curved transport path be O, when the center position of the workpiece when it is closest to the laser emission reference point is defined as P2, let the angle P1 - O - P2 be θ1, let the central angle of the arc region on the surface of the workpiece where the laser is irradiated be θ2, let the radius of the transport path circle be R, let the radius of the cylindrical surface of the workpiece be r, when the depth of focus of the laser is DoF, the relationship R(1 - cosθ1) + r(1 - cos(θ2 / 2)) < 2×DoF is satisfied, The best focus position of the laser is on the center side of the curved transport path rather than the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point. The laser irradiation device according to claim 1.

8. A laser irradiation device that irradiates the surface of the workpiece transported along a curved transport path, when viewed from a direction orthogonal to the plane including the transport path circle along the curved transport path, when the straight line direction passing through the center of the transport path circle and the front position (c) of the workpiece when the workpiece is closest to the laser emission reference point is defined as the Y-axis direction, The laser irradiation device according to claim 1, wherein an intermediate position in the Y-axis direction between a laser irradiation start point of the workpiece when laser irradiation of the workpiece is started and a front position of the workpiece when the workpiece is closest to the laser emission reference point is set to be the best focus position of the laser.

9. A laser irradiation device that irradiates a surface of a workpiece conveyed along a curved conveyance path, when viewed from a direction orthogonal to a plane including a conveyance path circle along the curved conveyance path, The laser irradiation device according to claim 1, wherein the laser emission reference point is arranged on a straight line passing through the center position of the workpiece when the workpiece is closest to the laser emission reference point and the center of the conveyance path circle.

10. A laser irradiation device that irradiates a surface of a workpiece conveyed along a curved conveyance path, when viewed from a direction orthogonal to a plane including a conveyance path circle along the curved conveyance path, The laser irradiation device according to claim 1, wherein the laser emission reference point is arranged within a range of less than ±5° in the circumferential direction centered on the center position of the workpiece when the workpiece is closest to the laser emission reference point, with reference to a straight line passing through the center position of the workpiece when the workpiece is closest to the laser emission reference point and the center of the conveyance path circle.

11. A laser irradiation method for irradiating a laser to an irradiation area of a workpiece to be conveyed, when the laser is two-dimensionally scanned in scanning directions intersecting each other on the surface of the workpiece, among the scanning directions intersecting each other, when the direction with a longer scanning distance in one scan is defined as the main scanning direction and the direction intersecting the main scanning direction is defined as the sub-scanning direction, the laser is scanned so that the main scanning direction is along the conveyance direction of the workpiece with respect to the irradiation area where the size in the main scanning direction is equal to or larger than the size in the sub-scanning direction.

12. Conveying means for conveying a workpiece, A laser irradiation device that irradiates a surface of the workpiece to be conveyed to form an image pattern, A laser irradiation system comprising: The laser irradiation device includes: A laser oscillation source that oscillates the laser, Scanning means for two-dimensionally scanning the laser oscillated from the laser oscillation source in scanning directions intersecting each other on the surface of the workpiece, Comprising: When, among the scanning directions intersecting each other, the direction with a longer scanning distance in one scan is defined as the main scanning direction, and the direction intersecting the main scanning direction is defined as the sub-scanning direction, the laser irradiation system is characterized in that the scanning means scans the laser so that the main scanning direction is along the conveyance direction of the workpiece with respect to the irradiation region in which the size in the main scanning direction is equal to or larger than the size in the sub-scanning direction.

13. A workpiece on which a modified portion is formed on the surface by the laser irradiation method according to Claim 11, wherein the modified portions are formed so as to be arranged continuously along the conveyance direction of the workpiece conveyed during laser irradiation.

14. In a region where two or more rows of image lines in which at least three or more modified portions are arranged continuously in the conveyance direction of the workpiece are formed in a direction intersecting the conveyance direction, there exists a portion where the interval between adjacent modified portions on each of the image lines is the largest, The workpiece according to Claim 13, wherein the number of combinations of the image lines in which the maximum gap positions where the intervals are the largest are different from each other is more than half of the total number of the image lines.

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