EP4680427A1

EP4680427A1 - Laser irradiation apparatus, laser irradiation method, and laser irradiation system

Info

Publication number: EP4680427A1
Application number: EP24709174.7A
Authority: EP
Inventors: Toshishige Fujii
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2023-03-13
Filing date: 2024-02-26
Publication date: 2026-01-21
Also published as: JP2024129473A; WO2024189445A1

Abstract

A laser irradiation apparatus includes an irradiator to start irradiating an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and end irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

Description

FN202304987

[DESCRIPTION]

[Title of Invention]

LASER IRRADIATION APPARATUS, LASER IRRADIATION METHOD, AND LASER IRRADIATION SYSTEM

[Technical Field]

[0001]

Embodiments of the present disclosure relate to a laser irradiation apparatus, a laser irradiation method, and a laser irradiation system.

[Background Art]

[0002]

Some laser irradiation apparatuses that irradiate an object conveyed by, for example, a belt conveyor with a laser beam are known.

For example, a configuration of a laser irradiation apparatus that irradiates an object held on the outer peripheral surface of a rotating cylindrical roll with a laser beam is disclosed in PTL 1.

As described above, in the case where an object is held on the outer peripheral surface of a rotating cylindrical roll and the object is conveyed along a curved conveyance path, the accuracy of laser irradiation may be decreased in comparison with the case where the object is conveyed along a linear conveyance path.

[Citation List]

[Patent Literature]

[0003]

[PTL 1]

Japanese Unexamined Patent Application Publication No. 2021-37685

[Summary of Invention]

[Technical Problem]

[0004]

An object of the present disclosure is to increase the accuracy of laser irradiation to the object to be conveyed along the curved conveyance path.

[Solution to Problem]

[0005]

According to an embodiment of the present disclosure, a laser irradiation apparatus includes an irradiator to start irradiating an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and end irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

According to an embodiment of the present disclosure, a laser irradiation method including: starting an irradiation to an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction of the object; and ending the irradiation to the object with the laser beam at an FN202304987 upstream position upstream from the downstream position on the object in the conveyance direction.

According to an embodiment of the present disclosure, a laser irradiation system includes a conveyor having a curved conveyance path to convey an object along the curved conveyance path in a conveyance direction and the laser irradiation apparatus. The laser irradiation apparatus starts irradiating the object conveyed along the curved conveyance path in the conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and ends irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction. [Advantageous Effects of Invention] [0006]

According to an embodiment of the present disclosure, the accuracy of laser irradiation to the object to be conveyed along the curved conveyance path can be increased.

[Brief Description of Drawings] [0007]

The accompanying drawings are intended to depict example embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

[FIG. 1]

FIG. 1 is a side view of a laser irradiation system including a laser irradiation apparatus according to a first embodiment of the present disclosure;

[FIG. 2]

FIG. 2 is a plan view of the laser irradiation system according to the first embodiment of the present disclosure;

[FIG. 3]

FIG. 3 is a block diagram illustrating a hardware configuration of a controller according to the first embodiment of the present disclosure;

[FIG. 4]

FIG. 4 is a block diagram illustrating a functional configuration of the controller according to the first embodiment of the present disclosure;

[FIG. 5A]

FIG. 5A is a schematic diagram illustrating a concave portion formed on the surface of a container by changing the properties of the container by laser irradiation, according to the first embodiment of the present disclosure;

[FIG. 5B]

FIG. 5B is a schematic diagram illustrating another concave portion formed on the surface of a container by changing the properties of the container by laser irradiation, according to the first embodiment of the present disclosure; FN202304987

[FIG. 5C]

FIG. 5C is a schematic diagram illustrating a crystalized portion formed on the surface of a container by changing the properties of the container by laser irradiation, according to the first embodiment of the present disclosure;

[FIG. 5D]

FIG. 5D is a schematic diagram illustrating a foamed portion formed inside a container by changing the properties of the container by laser irradiation, according to the first embodiment of the present disclosure;

[FIG. 6A]

FIG. 6A is a diagram illustrating a relation between an effective focal range and a laser irradiation region on the container conveyed along a curved conveyance path, according to the first embodiment of the present disclosure;

[FIG. 6B]

FIG. 6B is a diagram illustrating a relation between an effective focal range and a laser irradiation region on the container conveyed along a linear conveyance path, according to the first embodiment of the present disclosure;

[FIG. 7]

FIG. 7 is a plan view of the laser irradiation system that sequentially irradiates a container with a laser beam from a downstream position in the conveyance direction, according to the first embodiment of the present disclosure;

[FIG. 8]

FIG. 8 is a plan view of the laser irradiation system that sequentially irradiates a container with a laser beam from an upstream in the conveyance direction, according to the first embodiment of the present disclosure;

[FIG. 9]

FIG. 9 is a graph of a relation between a beam diameter of the laser beam and the depth of the focus;

[FIG. 10]

FIG. 10 is a graph of a relation between a visibility value and a defocus amount;

[FIG. 11]

FIG. 11 is a side view of a laser irradiation region on a container according to the first embodiment of the present disclosure;

[FIG. 12]

FIG. 12 is a plane view of a configuration of a laser irradiation system including a laser irradiation apparatus according to a second embodiment of the present disclosure;

[FIG. 13]

FIG. 13 is a diagram illustrating laser irradiation spots according to an embodiment of the present disclosure;

[FIG. 14]

FIG. 14 is a graph illustrating a relation between a length of a line pattern and productivity; FN202304987

[FIG. 15]

FIG. 15 is a plane view of a configuration of a laser irradiation system including a laser irradiation apparatus according to a third embodiment of the present disclosure;

[FIG. 16]

FIG. 16 is a side view of a container used in the third embodiment of the present disclosure;

[FIG. 17]

FIG. 17 is a graph of a relation between a distance from the center position of the pattern and a visibility value;

[FIG. 18]

FIG. 18 is a plan view of a deviation amount of an emission point from an optimum position;

[FIG. 19]

FIG. 19 is a side view of an order of laser irradiation according to an embodiment of the present disclosure;

[FIG. 20]

FIG. 20 is a side view of a laser irradiation system including an airflow generation unit according to an embodiment of the present disclosure;

[FIG. 21]

FIG. 21 is a diagram illustrating a relation between an order of laser irradiation and an airflow direction;

[FIG. 22]

FIG. 22 is a diagram illustrating an image capturing system of a container according to an embodiment of the present disclosure;

[FIG. 23]

FIG. 23 is a diagram illustrating the image capturing system of FIG. 22 including a white diffusing surface according to an embodiment of the present disclosure;

[FIG. 24]

FIG. 24 is a diagram illustrating a container having an image portion and a portion other than the image portion captured by the image capturing system of FIG. 22, according to an embodiment of the present disclosure;

[FIG. 25]

FIG. 25 is a graph of a relation between a G signal and a lightness converted by a third order polynomial;

[FIG. 26]

FIG. 26 is a graph of a relation between an image lightness L*o and a subject evaluation score;

[FIG. 27]

FIG. 27 is a graph of a relation between a difference (AL*) between the lightness of an image and the lightness of a portion other than the image and the subjective evaluation score;

[FIG. 28]

FIG. 28 is a graph of a relation between x and Y in the equation of Y = 1-exp (-x); FN202304987

[FIG. 29]

FIG. 29 is a graph of a relation between the subjective evaluation score and the visibility value;

[FIG. 30]

FIG. 30 is a graph of a relation between an evaluation rank and the visibility value; and

[FIG. 31]

FIG. 31 is a plan view of a laser irradiation system in which a laser irradiation apparatus is disposed inside of the center of a conveyance path, according to an embodiment of the present disclosure.

[Description of Embodiments]

[0008]

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.

[0009]

A laser irradiation apparatus according to embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, the same or like reference signs denote like elements having substantially the same or corresponding configurations, and descriptions thereof may be omitted.

[0010]

FIG. 1 is a side view of a laser irradiation system including a laser irradiation apparatus according to a first embodiment of the present disclosure, and FIG. 2 is a plan view of the laser irradiation system according to the first embodiment of the present disclosure.

[0011]

The laser irradiation system 1000 illustrated in FIG. 1 includes a laser irradiation apparatus 100, a conveyance apparatus 200, and a controller 400. In FIG. 2, the laser irradiation system 1000 illustrated in FIG. 1 further includes a conveyance detector 300.

[0012]

Configuration of Laser Irradiation Apparatus

The laser irradiation apparatus 100 is an apparatus that irradiates an object to be conveyed by the conveyance apparatus 200 with a laser beam L. In an embodiment of the present disclosure, the object includes the container 1 such as a polyethylene terephthalate (PET) bottle. When the laser irradiation apparatus 100 irradiates the container 1 with the laser beam L, the properties of the container 1 are changed, and a pattern is formed on the surface of the FN202304987 container 1. The pattern formed on the container 1 includes a character, a code such as a barcode, a figure, or an image. For example, the pattern includes information such as a name of a content stored in the container 1, an identification number, a manufacturer, or a manufacturing date. The position at which the pattern is formed in the container 1 may be the outer surface of the container 1 or the inner surface of the container 1.

[0013]

In the following description, the laser irradiation apparatus according to an embodiment of the present disclosure will be described with reference to the case where a pattern is formed on the surface of a container by laser irradiation. However, the laser irradiation apparatus according to an embodiment of the present disclosure can be applied to an object other than a container when a pattern is formed on the surface of the object.

[0014]

Configuration of Laser Irradiation Apparatus

The laser irradiation apparatus 100 includes a laser irradiation device 5 including a laser oscillator 11, an optical system 12, a deflector 13, a light condenser 14.

[0015]

Laser Oscillator

The laser oscillator 11 is a light oscillator to oscillate a laser beam L. In an embodiment of the present disclosure, a pulse laser oscillation device 10 is used as the laser oscillator 11. The pulse laser oscillation device 10 emits the laser beam L by repeating the blinking at short time intervals. As the laser oscillator 11, a continuous-wave (CW) oscillation laser device may be used instead of the pulse laser oscillation device 10. The CW oscillation laser device is a laser oscillator that continuously oscillates a laser beam.

[0016]

The pulse laser oscillation device 10 oscillates a substantially parallel pulse-like laser beam. The pulse laser oscillation device 10 is configured to switch oscillation (ON) and nonoscillation (OFF) based on data of a pattern formed in the container 1. The pulse laser oscillation device 10 can switch three oscillation waves, specifically, a fundamental wave having an oscillation wavelength of 1064 nanometers (nm), a second harmonic wave having an oscillation wavelength of 532 nm, and a third harmonic wave having an oscillation wavelength of 355 nm. For example, a pulse laser oscillation device of Talisker Ultra355-4 manufactured by Coherent Corp, based on a fiber laser can be applied. The laser beam L has a pulse with of 15 picoseconds (ps) or less at any oscillation wavelength. The repetition frequency of the laser beam can be preferably selected in a range from a single shot to 200 kirohertz (kHz). The laser beam L has a beam diameter of approximately 2.0 millimeters (mm) for the fundamental wave, approximately 1.4 mm for the second harmonic wave, and approximately 1.3 mm for the third harmonic wave.

[0017]

Optical System FN202304987

The optical system 12 is an optical system to adjust the beam diameter of the laser beam L oscillated from the laser oscillator 11. In an embodiment of the present disclosure, the optical system 12 includes the beam expander 9. When the pulse laser oscillation device 10 is used as the laser oscillator 11, the beam expander 9 magnifies the beam diameter of the laser beam L at a predetermined magnification ratio and emits the laser beam L as a substantially parallel laser beam.

[0018]

Deflector

The deflector 13 deflects the laser beam L whose beam diameter is adjusted by the optical system 12. The deflector 13 includes, for example, a first galvano mirror 15 and a second galvano mirror 16. Either one of the two galvano mirrors may be a polygon mirror. The first galvano mirror 15 deflects the laser beam L whose beam diameter is adjusted by the optical system 12 toward the second galvano mirror 16. The second galvano mirror 16 deflects the laser beam L deflected by the first galvano mirror 15 toward the light condenser 14. [0019]

The first galvano mirror 15 is disposed on the upstream of the optical axis of the laser beam L. The first galvano mirror 15 deflects the laser beam L in a direction perpendicular to the incident direction of the laser beam L (a positive direction of the Z-axis in FIG. 1). The first galvano mirror 15 is configured to swing in the directions of the arrow E in FIG. 2 by a driving source such as a motor. When the first galvano mirror 15 is swung, the object is scanned with the laser beam L from the beam expander 9 in the conveyance direction of the object (the direction of the arrow F in FIG. 2). As a result, the control of the scanning by the first galvano mirror 15 is determined based on the conveyance speed of the container 1. [0020]

On the other hand, the second galvano mirror 16 is disposed on the downstream of the optical axis of the laser beam E. The second galvano mirror 16 scans the object with the laser beam L in a direction intersecting the scanning direction of the first galvano mirror 15 (the direction of the arrow G in FIG. 1).

[0021]

Eight Condenser

The light condenser 14 condenses the laser beam L deflected by the deflector 13 to the container 1. Specifically, the light condenser 14 condenses the laser beam L to a predetermined position at which the container 1 is irradiated with the laser beam L. The light condenser 14 includes, for example, an 1'0 lens 17. The 1'0 lens 17 is a lens designed and manufactured so that the scanning speed of the laser beam L passing through the peripheral and the scanning speed of the laser beam L passing through the center are substantially constant. The laser beam L that enters the f9 lens 17 from the deflector 13 is condensed by the 1'0 lens 17 and emitted to the container 1. The 1'0 lens 17 may include one lens or a combination of multiple lenses. The function of the ft) lens 17 may be achieved by a configuration including an optical element such as a mirror other than a lens. FN202304987

[0022]

Configuration of Conveyance Apparatus

A configuration of the conveyance apparatus 200 will be described below.

[0023]

The conveyance apparatus 200 is an apparatus that conveys the container 1. Examples of the conveyance apparatus 200 include a belt conveyor. As illustrated in FIG. 2, the conveyance apparatus 200 according to an embodiment of the present disclosure has a curved conveyance path 20. In this case, the container 1 is sequentially conveyed along the arc of the curved conveyance path 20. While the container 1 is being conveyed by the conveyance apparatus 200, the laser irradiation apparatus 100 irradiates the container 1 with the bema laser L from the downstream position of the container 1 in the conveyance direction F of the container 1 (referred to as “conveyance direction” below). Then, the laser irradiation apparatus 100 irradiates the upstream position of the container 1 with the laser beam E.

[0024]

Configuration of Conveyance Detector

The configuration of the conveyance detector 300 will be described below.

[0025]

The conveyance detector 300 detects the container 1 conveyed to the laser irradiation position on the conveyance path 20. The conveyance detector 300 is disposed at a position upstream from the laser irradiation position in the conveyance direction F. Specifically, the conveyance detector 300 according to an embodiment of the present disclosure includes an optical sensor including a light emitting element 31 and a light receiving element 32. The light emitting element 31 and the light receiving element 32 are disposed at positions upstream from the laser irradiation position in the conveyance path 20 in the conveyance direction F so as to face each other across the conveyance path 20.

[0026]

When the container 1 passes a position between the light emitting element 31 and the light receiving element 32, the light beam emitted from the light emitting element 31 toward the light receiving element 32 is blocked by the container 1. As a result, the container 1 is detected. The conveyance detector 300 detects the container 1 and acquires detection information including a time of detection. Then, the conveyance distance from the container 1 to the laser irradiation position and the conveyance velocity are calculated based on the detected information. The time when the container 1 enters the laser irradiation position is calculated based on the conveyance distance and the conveyance velocity.

[0027]

Configuration of Controller

The configuration of the controller 400 will be described. The controller 400 controls the laser irradiation system 1000.

[0028] FN202304987

FIG. 3 is a block diagram illustrating a hardware configuration of a controller 400 according to the first embodiment of the present disclosure. The controller 400 is implemented by a computer or a configuration similar to a computer.

[0029]

As illustrated in FIG. 3, the controller 400 includes a central processing unit (CPU) 401, a read-only memory (ROM) 402, a random-access memory (RAM) 403, a hard disk (HD) 404, and a hard disk drive (HDD) controller 405, and a display 406. The controller 400 includes an external device connection interface (I/F) 408, a network I/F 409, a bus line 410, a keyboard 411, a pointing device 412, a digital versatile disk rewritable (DVD-RW) drive 414, and a media VF 416.

[0030]

The CPU 401 is a processor and controls the overall operation of the controller 400. The ROM 402 is a memory that stores a program used for driving the CPU 401 such as an initial program loader (IPL).

[0031]

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

[0032]

The display 406 displays various information such as a cursor, a menu, a window, characters, or images. The external device connection I/F 408 is an interface for connecting various external devices. In this case, the external devices include the laser oscillator 11 (pulse laser oscillation device 10), the deflector 13 (galvano mirrors 15, 16), and the conveyance detector 300. Further, a universal serial bus (USB) memory, or a printer can also be connected.

[0033]

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

[0034]

The keyboard 411 is an input device including multiple keys for inputting characters, numerical values, or various instructions. The pointing device 412 is an input device for selecting and executing various instructions, selecting a processing object, or moving a cursor.

[0035]

The DVD-RW drive 414 controls reading or writing of various data to or from the DVD-RW 413 serving as a removable recording medium. However, the recording medium is not limited to the DVD-RW. The media I/F 416 controls the media 415 such as a flash memory to read or write (store) data.

[0036] FN202304987

The controller 400 may not include all the hardware components. Depending on a configuration of using the laser irradiation apparatus 100, there may be hardware that is not included. Further, the laser irradiation apparatus 100 may include all of the hardware and functional configuration of the controller 400, or some of the hardware and functional configuration may be connected to the outside of the laser irradiation apparatus 100. [0037]

The functional configuration of the controller 400 will be described below with reference to FIG. 4.

[0038]

As illustrated in FIG. 4, the controller 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.

[0039]

Since the CPU 401 executes a predetermined program and outputs a control signal via the external device connection I/F 408, each function of the control data generation unit 44, the laser irradiation control unit 45, and the laser scanning control unit 46 is achieved. An electronic circuit or an electric circuit such as an application-specific integrated circuit (ASIC) or an field-programmable gate array (FPGA) may be added to the hardware configuration of the controller 400, and the electronic circuit or the electric circuit may achieve a part or all of the functions of each component. The function of the storage unit 43 is implemented by the HD 404.

[0040]

The irradiation data input unit 41 receives irradiation data according to which the laser irradiation apparatus 100 irradiates the container 1 with a laser beam. The irradiation data includes data relating to a pattern to be formed on the container 1. The irradiation data may include data other than the pattern.

[0041]

The irradiation data may be recorded in an external device such as a personal computer (PC) or a scanner. Alternatively, the irradiation data may be input by the user via the keyboard 411 or the pointing device 412 of the controller 400.

[0042]

The irradiation data input unit 41 outputs the input irradiation data to the control data generation unit 44 and the profile data specifying unit 42. The irradiation data input from the irradiation data input unit 41 may be temporarily stored in the storage unit 43. Since the irradiation data varies depending on the shape of the container 1, the irradiation data corresponding to the type of the container 1 may be stored in the storage unit 43 in advance. [0043]

The profile data specifying unit 42 specifies the profile data from the storage unit 43. The profile data is data that determines an irradiation region and a non-irradiation region when the container is irradiated with the laser beam. The profile data is also data that determines an FN202304987 acceleration, a period of acceleration or deceleration, and a period of constant velocity when the operation speed of the laser irradiation apparatus 100 is accelerated.

[0044]

The profile data is stored in the storage unit 43. The timing of storing the profile data may be in advance, or the profile data may be temporarily stored in the storage unit 43 when the scanning and the irradiation are executed.

[0045]

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 that controls the laser irradiation apparatus 100. Specifically, the control data includes data that controls the laser oscillator 11 and the deflector 13.

[0046]

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.

[0047]

The laser irradiation control unit 45 controls the irradiation of the laser beam L oscillated from the laser oscillator 11 based on the control data. The laser scanning control unit 46 controls the deflector 13 based on the detected information detected by the conveyance detector 300.

[0048]

When the laser oscillator 11 includes multiple pulse laser oscillation devices 10, the laser irradiation control unit 45 independently controls each of multiple pulse lasers.

[0049]

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

[0050]

The laser scanning control unit 46 controls the deflection of the laser beam L by the deflector 13 based on the control condition data. Specifically, the laser scanning control unit 46 controls the on-off operation of the first galvano mirror 15 and the second galvano mirror 16. [0051]

In the laser irradiation system 1000 according to an embodiment of the present disclosure, when the container 1 is conveyed along the conveyance path 20, the container 1 is detected by the conveyance detector 300 disposed upstream from the laser irradiation position in the conveyance direction. The controller 400 determines the timing when the laser irradiation apparatus 100 irradiates the container 1 with the laser beam L, based on the result that the conveyance detector 300 has detected the container 1. When the container 1 reaches the laser irradiation position, the laser irradiation apparatus 100 irradiates the container 1 with the laser FN202304987 beam L under the control of the controller 400, and a pattern is formed on the surface of the container 1.

[0052]

Changes in Properties of Container

Changes in properties of the container 1 by laser irradiation will be described. FIGS. 5A to 5D are diagrams illustrating changes in the properties of the container 1 according to the first embodiment of the present disclosure. The properties of the container 1 are changed in the order of FIGS. 5A, 5B, 5C, and 5D by laser irradiation. As a result, a pattern is formed in the container 1.

[0053]

In FIG. 5A, a concave portion 2 formed by evaporation of the surface of the container 1 is illustrated. In FIG. 5B, a concave portion 2 formed by melting the surface of the container 1 is illustrated. In the case of FIG. 5B, the peripheral edge of the concave portion 2 is raised as compared with FIG. 5A.

[0054]

In FIG. 5C, the surface of the container 1 is changed to have a crystallized portion. In FIG. 5D, the inside of the container 1 is changed to have a foamed portion. The concave portion can be formed by melting the container 1 by the irradiation of a CW laser beam having wavelengths of 355 nm to 1064 nm. Further, when the container 1 is continuously irradiated with the laser beam L even after the container 1 has melted, the inside and the surface of the container 1 can be foamed and become hazy.

[0055]

In order to generate the crystallization state, the temperature of a portion of the container 1 (e.g., PET) is rapidly increased by the CW laser irradiation. The CW laser has wavelengths of 355 nm to 1064 nm. Then, for example, the output of the CW laser is decreased to gradually cool the portion of the container 1. As a result, the portion of the container is crystallized and become hazy. By contrast, when the portion of the container 1 is rapidly cooled by turning off the CW laser after increasing the temperature of the portion of the container 1, the portion becomes amorphous and transparent.

[0056]

The changes of the properties of the container 1 are not limited to those illustrated in FIG. 5. Other types of resin may be used instead of PET, and the properties of the resin may be changed by yellowing, oxidation, or surface modification. The color and material of the resin of the container 1 are not limited to those of any types of resin as long as a pattern can be formed by the irradiation of the laser beam L. When the container 1 is irradiated with the laser beam L, the container 1 may contain a contained object or may not contain a contained object. The type or color of the content contained in the container 1 is not limited to that of any content.

[0057]

Difficulty in Laser Irradiation in Curved Conveyance FN202304987

Difficulty in laser irradiation to the object (container 1) conveyed in a curved conveyance path will be described.

[0058]

In FIG. 6A, the container 1 is to be conveyed along the curved conveyance path 20. In FIG. 6 A, the positions (1), (2), and (3), an angle a and a focal range H are illustrated. [0059]

The positions (1), (2), and (3) represent corresponding positions of the container 1 when the container 1 is conveyed along the curved conveyance path 20. The container 1 is conveyed via the positions (1), (2), and (3) in this order along the curved conveyance path 20, and the laser irradiation apparatus irradiates the container 1 with the laser beam L from a laser irradiation start point al to a laser irradiation end point b3. The position (1) is a position of the container 1 when the laser irradiation to the container 1 is started. The position (2) is a position of the container 1 when the container 1 comes closest to the emission point Q at which the laser beam is emitted from the deflector 13. The position (3) is a position of the container 1 when the laser irradiation to the container 1 is ended. In this case, the emission point Q of the deflector 13 is not the emission point of the first galvano mirror 15 disposed on the upstream of the optical axis of the laser beam L but the emission point of the second galvano mirror 16 disposed on the downstream of the optical axis of the laser beam L. [0060]

FIG. 6B is a diagram illustrating a case where the container 1 is conveyed along the linear conveyance path 21. In FIG. 6B, the positions (1)', (2)', and (3)', the angle a and the focal range H are illustrated. The positions (1)', (2)', and (3)' represent corresponding positions of the container 1 when the container 1 is conveyed along the linear conveyance path 21. The container 1 is conveyed via the positions (1), (2), and (3) in this order along the linear conveyance path 21. The position (1)’ is a position of the container 1 when the laser irradiation to the container 1 is started. The position (2)’ is a position of the container 1 when the container 1 comes closest to the emission point Q at which the laser beam L is emitted from the deflector 13. The position (3)’ is a position of the container 1 when the laser irradiation to the container 1 is ended.

[0061]

The angle a represents the angle of the laser irradiation region J from the laser irradiation start point al to the laser irradiation end point b3. The angle a is the same in the case where the container 1 is conveyed along the curved conveyance path 20 and in the case where the container 1 is conveyed along the linear conveyance path 21. In both cases where the container 1 is conveyed along the curved conveyance path 20 and where the container 1 conveyed along the linear conveyance path 21, the laser irradiation is sequentially executed from the laser irradiation start point al at the upstream of the laser irradiation region J in the conveyance direction.

[0062] FN202304987

The focal range H is an effective focal range in which the laser irradiation apparatus 100 irradiates the container 1 with the laser beam L. When the laser irradiation apparatus 100 irradiates the container 1 with the laser beam L within the focal range H, a pattern having a preferable visibility is formed on the container 1. In this case, the 1'0 lens 17 is used as the light condenser 14, and the focal range H is a range in a direction intersecting the laser emission direction (extending in the X-axis direction in FIG. 6) of the laser irradiation apparatus 100.

[0063]

The beam diameter of the laser beam increases as the focal position deviates from the center position N (best focus position) of the focal range H, and the irradiation accuracy of the laser beam decreases as the focal position deviates from the focal range H. In the case where the container 1 is conveyed along the curved conveyance path 20, since the laser irradiation start point al on the container 1 at a time when the laser irradiation is started and the laser irradiation end point b3 on the container 1 at a time when the laser irradiation is ended are out of the focal range H, the accuracy of the laser irradiation may decrease at the laser irradiation start point al, the laser irradiation end point b3, and the vicinity thereof.

[0064]

By contrast, when the container 1 is conveyed along the linear conveyance path 21, the laser irradiation region J on the container 1 is not deviated from the focal range H even if the container 1 is at any position.

[0065]

When the conveyance path is the linear conveyance path 21, the focal range H is more likely to include the laser irradiation region J on the container 1. For this reason, it is preferable that the laser irradiation is executed at a position in which the container 1 is conveyed along the conveyance path 21 having a linear path. However, in an actual production line, a space for disposing the laser irradiation apparatus 100 near the linear conveyance path 21 may not be held. In such a case, the laser irradiation apparatus 100 is disposed near the curved conveyance path 20, and the laser irradiation accuracy is decreased.

[0066]

Thus, the present inventor has conducted extensive studies in order to increase the laser irradiation accuracy described above. As a result, it was found that when the container 1 is conveyed along the curved conveyance path, there is a difference in the deviation amount of the laser irradiation position in the focal width direction (Y-axis direction in FIG. 6) from the best focus position N between the case where the laser irradiation is sequentially executed to the laser irradiation region J from the downstream in the conveyance direction and the case where the laser irradiation is sequentially executed to the laser irradiation region J from the upstream. The deviation amount of the laser irradiation position from the best focus position N in the focal width direction is referred to as a "defocus amount", and the difference in the defocus amount in each case will be described.

[0067] FN202304987

Difference in Defocus Amount

First, the defocus amount in the case where the laser irradiation apparatus 100 sequentially irradiates the laser irradiation region J of the container 1 with the laser beam L from the downstream in the conveyance direction will be described.

[0068]

FIG. 7 is a plan view of the laser irradiation system that sequentially irradiates a container with a laser beam from a downstream position in the conveyance direction, according to the first embodiment of the present disclosure.

[0069]

The laser irradiation start points al, a2, and a3 on the container 1 are set on the downstream in the conveyance direction F with respect to the laser irradiation end points bl, b2, and b3, respectively. Accordingly, when the container 1 reaches the laser irradiation start position (1) in the conveyance path 20, the laser irradiation system 1000 starts to irradiate the container 1 with the laser beam L at the laser irradiation start point al on the downstream. As the container 1 is conveyed to the position (2), the laser irradiation system 1000 continuously irradiates the container 1 with the laser beam L while shifting the laser irradiation position to the upstream in the conveyance direction F. The container 1 reaches the position (3), and the laser irradiation is ended at the laser irradiation end point b3.

In an embodiment of the present disclosure, a laser irradiation apparatus includes an irradiator to start irradiating an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and end irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

In an embodiment of the present disclosure, a laser irradiation method including starting an irradiation to an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction of the object; and ending the irradiation to the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

In an embodiment of the present disclosure, a laser irradiation system includes a conveyor having a curved conveyance path to convey an object along the curved conveyance path in a conveyance direction and the laser irradiation apparatus. The laser irradiation apparatus starts irradiating the object conveyed along the curved conveyance path in the conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and ends irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

[0070]

For example, the container 1 at the position (1) at a time when the laser irradiation is started will be described. The laser irradiation to the container 1 is executed within the range of an angle a (laser irradiation region J) represented by an angle al-A-bl connecting three points of the laser irradiation start point al, the center A of the container 1, and the laser irradiation end FN202304987 point bl. The centers A, B, and C are the centers of cross sections of the circles of the container 1 at the positions (1), (2), and (3), respectively. The cross-sectional shape of the container 1 is not limited to a circle, and may be a polygon. When the cross-sectional shape of the container 1 is a polygon, the center of a circumscribed circle circumscribing the polygon is set as the center of the container 1.

[0071]

As viewed from a direction perpendicular to a plane including the circle (referred to as a conveyance path circle K in the following description) disposed along the conveyance path 20, the container 1 is conveyed such that the front positions cl, c2, and c3 of the container 1 face the outside in a radial direction of the conveyance path circle K. In this case, the front positions cl, c2, and c3 at the positions (1), (2), and (3) correspond to intermediate positions (i.e., positions bisecting the laser irradiation region J) between the laser irradiation start points al, a2, and a3 and the laser irradiation end points bl, b2, and b3, respectively, at the positions (1), (2), and (3).

[0072]

For example, in the case where the front position C2 is the best focus position when the container 1 comes closest to the emission point Q of the deflector 13, the maximum defocus amount DI during the period from a time when the laser irradiation starts to a time when the container 1 comes closest to the emission point Q of the deflector 13 will be described. The maximum defocus amount DI is the distance between the position of the laser irradiation start point al and the front position c2 in the Y-axis direction (the distance between al' and c2'). The "Y-axis direction" is a linear direction passing the center O of the conveyance path circle K and the front position c2 of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13.

[0073]

The maximum defocus amount DI is expressed by the first mathematical expression below. [0074]

First Mathematical Expression

[0075] where R is a radius of the conveyance path circle K,

91 is an angle connecting three points that are the center position A of the container 1, the center O of the conveyance path circle, and the center position B of the container 1, r is a radius of the container 1, and

92 is an angle connecting three points that are the laser irradiation start point al, the center A, and the front position cl.

In the present description, the angle 92 is described as the angle of the container 1 at the position (1) at a time when the laser irradiation is started. Further, the angle 92 that connects the three points of the laser irradiation start point, the center of the container 1, and the front FN202304987 position of the container 1 is the same at any position (other positions (2) and (3)). Thus, the angle 92 represents the angle al-A-cl of the container 1 at the position (1), and may also represent the angle a2-B-c2 at the position (2), or the angle a3-C-c3 at the position (3).

[0076]

The defocus amount in the case where the laser irradiation apparatus 100 sequentially irradiates the laser irradiation region J of the container 1 with the laser beam L from the upstream in the conveyance direction will be described.

[0077]

As illustrated in FIG. 8, when the container 1 is sequentially irradiated with the laser beam L from the upstream in the conveyance direction F, the laser irradiation start points al, a2, and a3 are set on the upstream in the conveyance direction F with respect to the laser irradiation end points bl, b2, and b3, respectively, in FIG. 7. Accordingly, when the container 1 reaches the laser irradiation start position (1) on the conveyance path 20, the laser irradiation apparatus 100 starts to irradiate the container 1 with the laser beam L at the laser irradiation start point al on the upstream. As the container 1 is conveyed to the position (2), the laser irradiation apparatus 100 continuously irradiates the container 1 with the laser beam L while shifting the laser irradiation position to the upstream in the conveyance direction F. The container 1 reaches the position (3), and the laser irradiation is ended at the laser irradiation end point b3. The other configurations and functions are the same as those illustrated in FIG.

7.

[0078]

The maximum defocus amount D2 during the period from a time when the laser irradiation starts to a time when container 1 comes closest to the emission point Q of the deflector 13 will be described. The maximum defocus amount D2 is the distance between the position of the laser irradiation start point al and the front position c2 in the Y-axis direction (the distance between the laser irradiation start point al and the front position c2).

[0079]

The maximum defocus amount D2 is expressed by the second mathematical expression below.

[0080]

Second Mathematical Expression

[0081] where R is a radius of the conveyance path circle K, 91 is an angle connecting three points that are the center position A of the container 1, the center O of the conveyance path circle K, and the center position B of the container 1, r is a radius of the container 1, and

93 is an angle connecting three points that are the laser irradiation start point al, the center A, and the front position cl. FN202304987

In the present description, the angle 93 is described as the angle of the container 1 at the position (1) at time when the laser irradiation is started. However, the angle 93 that connects the three points of the laser irradiation start point, the center of the container 1, and the front position of the container 1 is the same at any position (other positions (2) and (3)). Accordingly, the angle 93 represents the angle al-A-cl of the container 1 at the position (1), and may also represent the angle a2-B-c2 at the position (2) or the angle a3-C-c3 at the position (3).

[0082]

As described above, the defocus amount DI expressed in the first mathematical expression in the case where the laser irradiation is sequentially executed from the downstream in the conveyance direction F and the defocus amount D2 expressed in the second mathematical expression in the case where the laser irradiation is sequentially executed from the upstream in the conveyance direction F are different from each other. In addition, in the case where the laser irradiation is sequentially executed from the upstream (FIG. 8), the defocus amount is greater than that in the case where the laser irradiation is sequentially executed from the downstream (FIG. 7) (D2 > DI) because the laser irradiation is started from a position far from the best focus position (the front position c in the position (2)).

[0083]

When the defocus amount increases, the focal position deviates from the center position (best focus position) of the focal range H and the beam diameter of the laser beam L increases. As a result, the accuracy of the laser irradiation decreases. Thus, the defocus amount remains within the focal range H, and the laser irradiation is sequentially executed from the downstream so that the defocus amount decreases.

[0084]

Relation between Effective Focal Range and Defocus Amount

The beam diameter of the laser beam increases as the focal position deviates from the center position (best focus position) of the focal range H, and the accuracy of the laser irradiation decreases as the focal position deviates from the focal range H.

[0085]

A test was conducted to examine the relation between the beam diameter of the laser beam and the depth of focus (DoF) from the best focus position. It was found that when the container was irradiated with a laser beam having, for example, an output of 30 watt (W) or more and 70 W or less, the accuracy of the laser irradiation could be maintained satisfactorily up to a beam diameter of 90 micrometers (pm) of the laser beam. FIG. 9 is a graph illustrating a relation between a beam diameter of the laser beam and the depth of the focus (DoF).

[0086]

In this test, an f9 lens having a focal length of 580 mm was used, and the beam diameter was measured as 1/e² by a beam profiler. The points plotted in X and Y indicate the diameters of the beam in the X-direction and the Y-direction that are perpendicular to each other. The FN202304987 focal length of the f9 lens is a value appropriately set according to the required pattern size, pattern accuracy, and productivity. When the focal length is longer, the beam diameter is greater and the lens is not suitable for a high-quality product. However, the problem of the large beam diameter can be solved by using a beam expander or by emitting multiple pulse beams. On the other hand, when the focal length is shorter, the accuracy of the laser irradiation increases. However, the productivity is lowered because the number of necessary dots increases.

[0087]

In FIG. 9, when the depth of focus increases from the position of “0” in the positive direction or the negative direction, the beam diameter gradually increases. The greater beam diameter is disadvantageous in the laser irradiation with high accuracy. When the laser output is set in the range of, for example, 30 W or more and 70 W or less, and the container was irradiated with the laser beam having the laser output, a preferable accuracy of the laser irradiation was maintained up to a beam diameter of 90 pm. To achieve a value of the beam diameter of the laser beam (90 pm or less) with such a preferable irradiation accuracy, it is preferable that the depth of focus (DoF) is set within a range of approximately ±8 mm based on the result of FIG. 9. In this case, the focal range H is 16 mm that is twice the depth of focus (DoF). In addition, when an f9 lens having a focal length of 920 mm was used, the results were almost the same as those illustrated in FIG. 9.

[0088]

In the case where the focal range H is in the above-described range (16 mm), the defocus amount DI in the case where the laser irradiation was executed from the downstream (FIG. 7) and the defocus amount D2 in the case where the laser irradiation was executed from the upstream (FIG. 8) were calculated, while the container was being conveyed under the conditions below.

[0089]

The pattern was formed by irradiating a region having a width of 40 mm on the container with a laser beam at a conveyance speed of 1000 mm/s and a distance between centers of the containers (conveyance pitch) of 120 mm. In this case, since the patterns are formed on about 500 containers per minute, the patterns are formed on about 8.3 containers per second. If the effective pattern formation time rate is 0.9, the pattern formation time (laser irradiation time) per container is 0.108 (= 1/8.3 x 0.9). In this case, the moving distance of the container during pattern formation (during laser irradiation) is 108 mm (= 0.108 x 1000 mm).

[0090]

When the radius R of the conveyance path circle is 200 mm, the radius r of the container is 36 mm, the angles 92 and 93 are both 31.4° in the case where a pattern is formed by irradiating a region having a width of 40 mm with a laser beam. The moving distance of the container from a time when the laser irradiation starts to a time when the container comes closest to the emission point Q of the deflector 13 is 54 mm, since it is a half of 108 mm, which is the total moving distance of the container during pattern formation. In this case, the angle 91 is 15.5°. FN202304987

[0091]

When the defocus amounts DI and D2 are calculated based on the first and second mathematical expressions in the case where the container is conveyed under the abovedescribed conditions, the defocus amount DI is 8.7 mm in the case where the container is sequentially irradiated with the laser beam from the downstream, and the defocus amount D2 is 18.8 mm in the case where the container is sequentially irradiated with the laser beam from the upstream. In other words, when the container is sequentially irradiated with the laser beam from the downstream, the defocus amount DI (8.7 mm) is smaller than the focal range H (16 mm), but when the container is sequentially irradiated with the laser beam from the upstream, the defocus amount D2 (18.8 mm) exceeds the focal range H (16 mm). Also from this result, it is preferable that the container is irradiated with the laser beam from the downstream rather than the from the upstream in order to keep the defocus amount within the focus range H.

[0092]

Laser Irradiation Method According to One Embodiment of the Present Disclosure As described above, the laser irradiation apparatus 100 according to the first embodiment of the present disclosure starts to irradiate the container 1 with a laser beam L from a downstream position of the container 1 (laser irradiation start point al) in the conveyance direction F and then irradiates an upstream position of the container 1 with the laser beam L. [0093]

In this way, since the laser irradiation apparatus 100 irradiates the container 1 with a laser beam L from the downstream, the laser irradiation can start from a closer position to the best focus position as compared to a case where the laser irradiation starts from the upstream. As a result, the maximum defocus amount DI can be reduced. Accordingly, the defocus amount DI can be maintained within the focus range H, and the irradiation accuracy of the laser beam L can be increased.

[0094]

Further, when a linear direction passing the center O of the conveyance path circle K and a front position c2 of the container 1 that is the position at which the container 1 comes closest to the emission point Q of the deflector 13 is defined as a Y-axis direction, it is preferable that the best focus position N is set at an intermediate position in the Y-axis direction between a laser irradiation start point al of the container 1 that is the point at which the laser irradiation to the container 1 is started and the front position c2 of the container 1 comes closest to the emission point Q of the deflector 13. Thus, it is preferable that the best focus position N is set to an intermediate position in the Y-axis direction of the defocus amount DI. Since the best focus position N is set at such a position, the laser irradiation region J on the container 1 is likely to be included in the focal range H [0095]

The defocus amount tends to increase as the conveyance speed of the container increases. For example, when the pattern forming speed (laser scanning speed) in the case where the FN202304987 conveyance speed of the container is 1000 millimeters per second (mm/s) is the limit performance of the laser irradiation apparatus, the pattern forming speed is not changed if the conveyance speed of the container is doubled to 2000 mm/s. As a result, the angle 91 increases to 31° from 15.5°. In other words, the moving distance of the container 1 conveyed during laser irradiation becomes longer. In this case, when the defocus amount DI is calculated based on the first mathematical expression in the case where the container is irradiated with the laser beam from the downstream, the defocus amount DI is 28.6 mm that is greater than the defocus amount (8.7 mm) in the case where the conveyance speed is one half.

[0096]

As described above, when the container is conveyed at a high conveyance speed, even if the laser irradiation is sequentially executed from the downstream, the defocus amount DI may become large and exceed the focal range H (twice the focal depth DoF).

[0097]

In addition to sequentially executing laser irradiation from the downstream, it is preferable to satisfy the relation expressed by the third mathematical expression below so that the defocus amount DI remains within the focal range H.

[0098]

Third Mathematical Expression

[0099]

D1 — R (1 “ cos 01 ) + r (1 “ cos ( 02 “ 01 ) ) < 2 x Dof where R is a radius of the conveyance path circle K,

91 is an angle connecting three points that are the center position A of the container 1, the center O of the conveyance path circle, and the center position B of the container 1, r is a radius of the container 1,

92 is an angle connecting three points that are the laser irradiation start point al, the center A, and the front position cl, and

DoF is the depth of focus.

The angle 91, the angle 92, R, and r in the third mathematical expression are the same as the angle 91, the angle 92, R, and r in the first mathematical expression. In the third mathematical expression, DoF represents the depth of focus. In other words, “2 x DoF" indicates a focal range H that is twice the focal depth.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An expression below is satisfied in a plane of the curved conveyance path having a shape of circle, R (1 - cos 91) + r (1 - cos (92 - 91)) < 2xDoF, where

91 is an angle AOB that connects three points A, O, and B, where: FN202304987

A is a center position of the object at a start of a laser irradiation; O is a center of the curved conveyance path in the plane; and

B is a center position of the object conveyed to an emission point at which the object is irradiated with the laser beam by the deflector,

92 is an angle al-A-cl that connects three points al, A, and cl, where al is the downstream position on the object, A is the center position of the object, cl is a front position of the object to be faced with the deflector, R is a radius of the curved conveyance path, r is a radius of the object, and

DoF is a depth of a focus of the laser beam. [0100]

FIG. 10 is a graph illustrating a relation between a visibility value of a pattern (accuracy of laser irradiation) and a defocus amount DI.

[0101]

In this test, the radius R of the conveyance path (conveyance path circle K) was set to 200 mm, which is considered to be the smallest in a real case, the radius r of the container was set to 36 mm, which is the radius of the PET bottle that is generally produced the most, and the values of the angles 91 and 92 were changed and a pattern was formed on the container. If the conveyance path is too large, the conveyance path approximates to a straight line, and a problem due to the magnitude of the defocus amount is less likely to occur. This is the reason why the radius R of the conveyance path was set to 200 mm in this test. The output of the laser irradiation apparatus was set to a value in the range of 30 W to 70 W, and the frequency of the laser was set to an optimum value in the range of 500 kHz to 3000 kHz. In terms of the f9 lens, an f9 lens having a focal length of 580 mm was used. Under these conditions described above, the laser irradiation apparatus irradiated the container with a laser beam, and the visibility of the obtained pattern was evaluated. The method of evaluating the visibility value will be described later, and in this case, the visibility value of "7.0" or more was determined as an acceptable value acceptable as a commercial product distributed in the market. Since the conditions under which the visibility value is determined to be good vary depending on, for example, the structure of the container or the type of content in the container, the acceptable visibility value in the present test is only a value given as an example. The quality of the pattern may be determined based on other evaluation criteria. [0102]

According to the results illustrated in FIG. 10, a preferable visibility value was obtained when the defocus amount DI was smaller than twice of the focal depth (2 x DoF) of the focal range H. As a result, when the third mathematical expression is satisfied, a preferable visibility value could be obtained.

[0103] FN202304987

To satisfy the relation expressed by the third mathematical expression, for example, it is conceivable that the positions of the laser irradiation start point al and the laser irradiation end point b3 are adjusted so that the laser irradiation region J on the container 1 illustrated in FIG. 7 decreases. Accordingly, the values of the angles 91 and 92 in the third mathematical expression can be set to appropriate values. The value of the angle 91 varies depending on the radius R of the conveyance path in addition to the conveyance speed. If the angle 91 is too large, the defocus amount DI increases. Thus, the angle 91 is preferably 2° or more and 25° or less, and more preferably 10° or more and 20° or less. The angle 92 is a value that varies depending on the size of the laser irradiation region J in addition to the size of the container. If the angle 92 is too large, the defocus amount increases. Thus, the angle 92 is preferably 20° or more and 40° or less, and more preferably 25° or more and 35° or less. [0104]

Productivity of Pattern Formation by Laser Irradiation Apparatus

The productivity of pattern formation by one laser irradiation apparatus 100 will be described below.

[0105]

The laser oscillator may include a continuous wave (CW) laser device other than a pulse laser oscillation device. However, since the pulse laser oscillation device is a laser device that repeats blinking at a short time interval, the productivity depends on the repetition frequency of the pulse laser. In the following description, the productivity of pattern formation will be described based on an example in which a pulse laser oscillation device is used as the laser oscillator.

[0106]

The conveyance speed V [mm/s] of the container is calculated by the fourth mathematical expression below.

[0107]

Fourth Mathematical Expression where W [mm] is the cross-sectional diameter of the container, d [mm] is the distance between the multiple containers in the conveyance direction, and X [piece/min] is the productivity of pattern formation.

[0108]

In addition, to maintain the productivity X, the time T allowed per scanning by the second galvano mirror 16 is calculated by the fifth mathematical expression below (inches are converted to mm).

[0109]

Fifth Mathematical Expression FN202304987

T „ 25. 4 a«X« (W + d) where W [mm] is the cross-sectional diameter of the container, d [mm] is the distance between the multiple containers in the conveyance direction, X [piece/min] is the productivity of pattern formation, and a [dpi] is the pixel density. [0110]

Further, the time At [seconds (s)] allowed per dot in the laser scanning direction is calculated by the sixth mathematical equation to maintain the productivity X.

[0111]

Sixth Mathematical Expression where Lz [mm] is a lateral width of the pattern forming region on the container in the laser scanning direction (the direction of arrow G in FIG. 1) intersecting the conveyance direction F (see FIG. 11).

[0112]

The fluence of the laser will be described below.

[0113]

The fluence F of the laser can be expressed by the equation below.

[0114]

P = E • v F = E / S,

[0115] where P [W] is the average output (light intensity) of the pulse laser, E [Jules] is the pulse energy per pulse, and v [heltz (Hz)] is represents the repetition frequency of the pulse laser. F [Jules/cm²] is the fluence, and S [cm²] is the area of the laser beam spot.

[0116]

The fluence F corresponds to the pulse energy divided by the area of the laser beam spot. The fluence of the base material constituting the container is a value obtained by dividing the pulse energy of the laser beam emitted from the pulse laser oscillation device by the area of the laser beam spot on the base material constituting the container.

[0117]

When a laser beam having a pulse width of nanosecond (ns) scale is used as the laser beam, a pattern is formed by thermal denaturation according to the absorption spectrum of the container. On the other hand, when a laser beam having a pulse width of a picosecond (ps) scale is used as the laser beam, a pattern is formed by thermal denaturation corresponding to each of an absorption spectrum and multiphoton absorption.

[0118] FN202304987

The multiphoton absorption is a nonlinear phenomenon in which an atom or a molecule absorbs multiple photons and is excited to a state of an electron and atom with a higher energy level by the laser irradiation as if the laser beam has a wavelength corresponding to 1/2 or 1/3 of an oscillation wavelength of the laser. When a laser beam having a pulse width of a picosecond scale is used, the container can be sublimated from a solid state without passing through a molten state, and a processing mark can be formed on the base material. [0119]

At this time, when a pulse laser oscillation device that can form a pattern of one dot by one pulse is selected as the required fluence, the pattern forming frequency becomes v [Hz] that is the repetition frequency.

[0120]

On the other hand, when the fluence of the laser irradiation apparatus is small and N pulses are required for forming a pattern of one dot, the pattern forming frequency is v/N [Hz], and thus the time required for forming a pattern of one dot is N/v [s], [0121]

In this case, At is allowed to have a value greater than N/v [s], and the container cannot be conveyed at a speed higher than the speed allowed for pattern formation by one scanning. In other words, the time allowed to form a pattern of one dot is the rate limiting factor of the productivity.

[0122]

FIG. 11 is a side view of a laser irradiation region on a container 1 according to the first embodiment of the present disclosure. The container 1 is irradiated with a laser beam in the longitudinal direction by using a pulse laser oscillation device. Multiple line patterns 3 are formed on the surface of the container 1. In this case, the irradiation region J is a formation region in which the patterns 3 are formed. The lateral width Lx of the irradiation region J is the width in the same direction as the conveyance direction F, and the longitudinal width Lz of the irradiation region J is the width in the direction intersecting the conveyance direction F. When the lateral width Lx of the irradiation region J is 40 mm and the resolution is 300 dot per inch (dpi), the lateral pitch between adjacent ones of the patterns 3, each of which is formed in the longitudinal direction of the container 1, is 0.084 mm (= 25.4/300), and 479 line patterns 3 are formed in the lateral width Lx of 40 mm.

[0123]

If the conveyance distance of the container to be conveyed during laser irradiation is 108 mm and 479 line patterns 3 are formed in the conveyance distance, one line pattern 3 is formed while the container moves 0.22 mm. In other words, when a pattern is formed on a container that is conveyed at high speed by using one laser irradiation apparatus, it is necessary to scan the container with a high-output laser beam at high speed.

[0124]

However, when the laser output is 50 W or more, the size of the laser irradiation apparatus becomes large. In addition, the large-sized laser irradiation apparatus increases cost because FN202304987 the cooling device for cooling is also large. Further, when laser irradiation is executed at a high speed, the parts of the laser irradiation apparatus are apt to be deteriorate and maintenance costs due to replacement of the parts are also required.

[0125]

On the other hand, since a small-sized laser irradiation apparatus having a laser output less than 50 W has low responsiveness and accuracy in focus adjustment, it is difficult to irradiate a container being conveyed at high speed with a laser beam with high accuracy. Thus, to achieve the high accuracy of laser irradiation using a small-sized laser irradiation apparatus, it is necessary to reduce the conveyance speed of the container. As a result, the productivity may be decreased.

[0126]

In order to examine the above-mentioned problem of productivity, the productivity in the case of pattern formation using one laser irradiation apparatus was examined.

[0127]

FIG. 12 is a plane view of a configuration of a laser irradiation system 1000’ including a laser irradiation apparatus 100’ according to a second embodiment of the present disclosure.

[0128]

As the 1'0 lens 17 in the laser irradiation apparatus 100’, an f9 lens having a focal length of 580 mm was used. The laser irradiation apparatus 100 continuously irradiated the container 1 conveyed along the curved conveyance path 20 with the laser beam L from the laser irradiation start point al to the laser irradiation end point b3. In addition, the laser irradiation system 1000' has the same configuration as the laser irradiation system 1000 illustrated in FIG. 1.

[0129]

In addition, in this test, the lateral width Lx of the laser irradiation region J was 30 mm, and the longitudinal width Lz was 45 mm. The laser output was set to a value in the range of 30 W to 70 W, and the laser frequency was set to an optimum value in the range of 500 kHz to 3000 kHz.

[0130]

A pattern of laser irradiation using the laser irradiation system 1000' is illustrated in FIG. 13. FIG. 13 is a diagram illustrating a laser irradiation spot according to an embodiment of the present disclosure. The laser irradiation spot 4 irradiated with the laser beam is represented by a circle, and the pattern 3 including multiple circles is illustrated. Multiple patterns 3 are arranged at a pitch Pl. The laser irradiation spots 4 are overlapped in the region P2 (overlap region). For example, when fifteen laser irradiation spots 4 are arranged in a line such that adjacent ones of the fifteen laser irradiation spots 4 overlap with the region P2 within a range in which ten laser irradiation spots 4 are arranged in a line such that adjacent ones of the ten laser irradiation spots 4 contact with each other without overlapping with each other (FIG. 13), the overlap ratio of the region P2 is 1.5. The diameter of the laser irradiation point 4 is defined as a width d, and the processing ratio U is expressed by the equation below. U = d / FN202304987

Pl Even under the same laser output condition, the accuracy of the pattern and the visibility value can be increased by increasing the number of overlapped patterns or the processing ratio U. However, since it becomes difficult to form a pattern within a limited time, the productivity decreases.

[0131]

In this test, the overlap ratio was 1.5 and the processing ratio was 70%. The change in productivity depending on the length of the line pattern in the longitudinal direction was examined when the line pattern was increased with an interval of 5 mm. The result is illustrated in FIG. 14.

[0132]

FIG. 14 is a graph of a relation between the length of the line pattern and the productivity. The productivity in the case where the visibility value of the pattern is 7.0 or more is illustrated in the vertical axis, and the length of the line pattern is illustrated in the horizontal axis. In the graph, the productivity in the case where the shortest length of the line pattern is 5 mm is set to 1 (i.e., reference productivity), and the productivity in the case where the line pattern is increased with an interval of 5 mm with reference to the reference productivity is illustrated as a relative value.

[0133]

It is found that the productivity decreases as the length of the line pattern increases. In this case, when the length of the line pattern was 45 mm, the relative value of the productivity was decreased to 0.28. Thus, when the pattern is lengthened in the longitudinal direction, it is difficult to form the pattern having a good visibility while maintaining high productivity by one laser irradiation apparatus 100.

[0134]

By contrast, when the pattern formed by one laser irradiation apparatus 100 is shortened in the longitudinal direction, the pattern can be formed with a good visibility while maintaining high productivity. In view of the above, in another embodiment of the present disclosure described below, the laser irradiation apparatus 100 includes multiple laser oscillators 11, and the pattern formed by one laser oscillator 11 is shortened in the longitudinal direction. The configuration of another embodiment of the present disclosure will be described below.

[0135]

Another Embodiment of the Present Disclosure

FIG. 15 is a plane view of a configuration of a laser irradiation system 1000A including a laser irradiation apparatus 100A according to a third embodiment of the present disclosure. [0136]

The laser irradiation apparatus 100A according to the third embodiment of the present disclosure includes laser units 5 A, 5B, and 5C as laser irradiation units. Each of the laser units 5A, 5B, and 5C includes an optical system 12, a deflector 13, and a light condenser 14 in addition to a laser oscillator 11, as in the laser irradiation apparatus 100.

[0137] FN202304987

The laser units 5A, 5B, and 5C are disposed along a curved conveyance path 20. The laser unit 5A (first laser unit), the laser unit 5B (second laser unit), and the laser unit 5C (third laser unit) are disposed in this order from the upstream in the conveyance direction F, and the container 1 to be conveyed is irradiated with a laser beam from the first laser unit, a laser beam from the second laser unit, and a laser beam from the third laser unit in this order. [0138]

FIG. 16 is a side view of a container used in the third embodiment of the present disclosure. [0139]

In the third embodiment of the present disclosure, the laser irradiation region J on the container 1 is divided into multiple regions JI, J2, and J3. The regions JI, J2, and J3 are divided in the longitudinal direction from the cap to the bottom surface of the container 1. In this case, the laser irradiation region J includes the laser irradiation regions JI, J2, and J3 that are different from each other and divided into multiple regions in a direction (longitudinal direction) intersecting the conveyance direction F. The multiple laser irradiation regions JI, J2, and J3 are not regions partitioned by, for example, visible lines, and are conceptually partitioned regions.

[0140]

In this way, since the laser irradiation region J on the container 1 is divided in the longitudinal direction, the length of each of the laser irradiation regions JI, J2, and J3 in the longitudinal direction is reduced. In the third embodiment of the present disclosure, each pattern in the laser irradiation regions JI, J2, and J3 that are shorter in the longitudinal direction is formed by the laser units, 5A, 5B, and 5C that are separate laser units, respectively. In other words, when the container 1 is conveyed, the laser unit 5A (first laser unit) irradiates a laser irradiation region of the container 1 with a laser beam, then the laser unit 5B (second laser unit) irradiates another laser irradiation region of the container 1 with a laser beam, and finally, the laser unit 5C (third laser unit) irradiates yet another laser irradiation region of the container 1 with a laser beam. At this time, the laser irradiation by each of the laser unit 5A, 5B, and 5C is executed from a downstream area of a corresponding one of the laser irradiation region JI, J2, and J3 in the conveyance direction F. A pattern may be formed on each laser irradiation region separately with a space between adjacent ones of the laser irradiation regions JI, J2, and J3. Alternatively, the pattern may be formed seamlessly without any space between adjacent ones of the laser irradiation regions JI, J2, and J3.

[0141]

As described above, in the third embodiment of the present disclosure, the laser irradiation apparatus 100 includes the multiple laser units 5A, 5B, and 5C. Since each of the laser units 5 A, 5B, and 5C irradiates the corresponding laser irradiation regions JI, J2, and J3 that are different from each other and divided in the longitudinal direction with the laser beam L, the laser irradiation time per laser irradiation unit can be reduced. In other words, since the multiple laser units 5A, 5B, and 5C irradiate the laser irradiation regions JI, J2, and J3 that are different from each other and divided in the longitudinal direction with the laser beams, a FN202304987 laser irradiation length in the longitudinal direction of one laser irradiation region by one laser irradiation unit becomes shorter than the case where one laser unit irradiates the overall irradiation region J with a laser beam. Thus, the laser irradiation time per laser irradiation unit can be reduced. Accordingly, even if the conveyance speed of the container is increased, laser irradiation can be executed with high accuracy, and the productivity and accuracy of the laser irradiation can be increased.

[0142]

For example, when the laser irradiation region J having a length of 45 mm in the longitudinal direction is divided into three regions in the longitudinal direction, the length of each one of the divided laser irradiation regions (i.e., the laser irradiation regions JI, J2, and J3) in the longitudinal direction is 15 mm. Referring to the test results illustrated in FIG. 14, the relative value of the productivity is 0.28 when the line pattern having a length of 45 mm in the longitudinal direction is formed. On the other hand, the relative value of the productivity is increased to 0.61 when the laser irradiation region J is divided into three equal regions in the longitudinal direction and the length of the line pattern in the longitudinal direction is 15 mm. As described above, the laser irradiation region J is divided into three regions in the longitudinal direction to reduce the length of each of the laser irradiation regions JI, J2, and J3 in the longitudinal direction, and the laser irradiation is executed to the laser irradiation regions JI, J2, and J3 by using different laser irradiation units. Thus, the laser irradiation can be executed with high accuracy while maintaining high productivity. According to the configuration of the third embodiment of the present disclosure, even when a small-sized laser irradiation apparatus is used, the laser irradiation can be executed with high accuracy to an object conveyed at high speed on the curved conveyance path without decreasing productivity.

[0143]

The number of divisions of the laser irradiation region J in the longitudinal direction and the number of laser irradiation units to be disposed are not limited to three, but may be two or four or more. If the installation space and cost of the laser irradiation apparatus are sufficient, the productivity and quality can be further increased by increasing the number of divisions of the laser irradiation region J and the number of laser irradiation units.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the irradiator includes multiple laser oscillators to respectively oscillate multiple laser beams, and the multiple laser oscillators respectively irradiate multiple laser irradiation regions, divided in an intersecting direction intersecting the conveyance direction, on the object with the multiple laser beams.

[0144]

In the laser unit 5A, the emission point Q at which the laser beam L is emitted from the deflector 13 is preferably disposed on the straight line Ml passing through the center O of the conveyance path circle K and the center A of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13 of the laser unit A. In the laser unit 5B, the FN202304987 emission point Q at which the laser beam L is emitted from the deflector 13 is preferably disposed on the straight line M2 passing through the center O of the conveyance path circle K and the center B of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13 of the laser unit B. In the laser unit 5C, the emission point Q at which the laser beam L is emitted from the deflector 13 is preferably disposed on the straight line M3 passing through the center O of the conveyance path circle K and the center C of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13 of the laser unit C. In these cases, the emission point Q of the deflector 13 is not the emission point of the first galvano mirror 15 disposed on the upstream of the optical axis of the laser beam L but the emission point of the second galvano mirror 16 disposed on the downstream of the optical axis. Since the emission point Q of the deflector 13 is disposed on the straight lines Ml, M2, and M3, the laser irradiation with high accuracy over a wide range in the lateral direction (conveyance direction F) in a short time can be achieved.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An emission point of the deflector is in a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle.

[0145]

FIG. 17 is a graph of the visibility of the pattern when the emission point Q of the deflector 13 is arranged at a position deviated from the optimum position.

[0146]

In FIG. 17, the solid line represents the relation between the deviation amount (distance) of the laser irradiation position from the center of the pattern and the visibility value when the emission point Q of the deflector 13 is on the straight lines Ml, M2, and M3. The chain line and the two-dot chain line in FIG. 18 represent the relation between the deviation amount (distance) of the laser irradiation position from the center of the pattern and the visibility value when the emission point Q of the deflector 13 is arranged to be deviated from the center of the pattern by the angle P illustrated in FIG. 18 with respect to the straight lines Ml, M2, and M3. The angle P illustrated in FIG. 18 is the deviation amount in the circumferential direction with respect to the center positions A, B, and C of the respective container 1 when the container 1 comes closest to the emission point Q of the deflector 13 of the respective laser units 5 A, 5B, and 5C with respect to the straight lines Ml, M2, and M3. The chain line in FIG. 17 represents the case where the deviation amount (angle P) is ±5° and the two-dot chain line in FIG. 17 represents the case where the deviation amount (angle P) is ±10°. [0147]

As the laser irradiation position deviates from the center of the pattern in the lateral direction, the visibility value of the pattern gradually decreases. In particular, when the deviation amount (angle P) was ±5° or ±10° and the laser irradiation position was separated from the FN202304987 center of the pattern by +15 mm, the visibility value was less than 7.0 that is the visibility value allowed as a commercial product in the market. By contrast, when the deviation amount (angle P) is less than ±5° (only the case where the deviation amount of 0° is only illustrated in FIG. 17), a visibility value of 7.0 or more was obtained even when the laser irradiation position was deviated from the center of the pattern in the lateral direction.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An emission point of the deflector is in a range greater than -5 degrees and smaller than +5 degrees from a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle in a circumferential direction of the object around the center position of the object.

[0148]

Thus, to form a pattern with high accuracy, it is preferable to arrange the emission point Q of the deflector 13 so that the deviation amount (angle P) from the straight lines Ml, M2, and M3 is less than 5°. The arrangement of the deflector 13 is not limited to the configuration including the multiple laser units 5A, 5B, and 5C, and may be applied to the configuration including one laser irradiation unit 5.

[0149]

In addition, the order of laser irradiation and the laser scanning direction for each of the divided laser irradiation regions JI, J2, and J3 were examined as described below. [0150]

The scanning direction of the laser beam in each of the laser irradiation regions JI, J2, and J3 includes a case where the scanning direction of the laser beam is from the laser irradiation start point al toward the upstream (lateral direction) in the conveyance direction F and a case where the scanning direction of the laser beam is from the laser irradiation start point al toward the direction (longitudinal direction) intersecting the conveyance direction F. In both cases, since the laser irradiation starts from the laser irradiation start point al on the downstream in the conveyance direction F, the above-described defocus amount can be reduced, and the laser irradiation with high accuracy can be easily achieved. However, when each laser irradiation region is scanned with the laser beam from the laser irradiation start point al toward the upstream (lateral direction) in the conveyance direction F, the laser irradiation position moves in a direction relatively away from the laser irradiation unit, and thus, the laser irradiation position may be far from the best focus position of the laser irradiation unit. Accordingly, in order to execute laser irradiation with high accuracy, it is preferable to scan the laser beam from the laser irradiation start point al in the direction (longitudinal direction) intersecting the conveyance direction, rather than scanning the laser beam from the laser irradiation start point al toward the upstream in the conveyance direction (lateral direction). FN202304987

In an embodiment of the present disclosure, in the laser irradiation apparatus, the laser irradiation apparatus starts irradiating the object with the laser beam moving from the downstream position on the object in a first intersecting direction intersecting the conveyance direction, shifts an irradiation position of the laser beam to another position upstream from the downstream position in the conveyance direction, and irradiates the object with the laser beam moving from said another position in a second intersection direction opposite to the first intersecting direction.

[0151]

For example, as illustrated in FIG. 19, each laser irradiation region is irradiated with the laser beam from the laser irradiation start point al in a direction intersecting the conveyance direction F (downward in FIG. 19). Then, the laser irradiation position is shifted upstream in the conveyance direction F, and the laser irradiation region is irradiated with the laser beam in a direction intersecting the conveyance direction F (upward in FIG. 19) . The laser irradiation described above is repeated, and the laser irradiation ends at the laser irradiation end point b3. [0152]

As described above, since the laser scanning direction from the laser irradiation start point al is set to the direction (longitudinal direction) intersecting the conveyance direction F, the defocus amount (the deviation amount of the laser irradiation position from the best focus position) can be further reduced as compared with the case where the laser scanning direction is set to the conveyance direction F (lateral direction). As a result, the accuracy of the laser irradiation is further increased. The scanning direction of the laser beam described above is not limited to the direction with respect to the container 1 having multiple divided laser irradiation regions JI, J2, and J3 as illustrated in FIG. 19, and can be applied to the container 1 having one laser irradiation region J.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An intermediate position in a Y-axis direction, between the downstream position on the object at a start of a laser irradiation and a front position of the object at which the object comes closest to an emission point of the deflector, is a best focus position of the laser beam in a plane of the curved conveyance path having a shape of circle. The Y-axis direction is a straight line passing a center of the conveyance path in the plane and the front position of the object.

[0153]

When the properties of the container are changed by irradiation of the container with the laser beam, smoke may be generated. The smoke includes water, benzene, aldehyde, and plasma that are scattered when the properties of the container are changed, and low molecules and high molecules that are scattered due to ablation. When the smoke is generated, the smoke tends to move upward. Accordingly, depending on the order of laser irradiation to the laser irradiation regions JI, J2, and J3, the smoke may cover the laser irradiation position, and the accuracy of laser irradiation may be decreased. In other words, when the laser irradiation is FN202304987 executed by moving the laser irradiation position from the lower side to the upper side, the smoke generated in the lower side moves to the upper side, and the accuracy of the laser irradiation at the upper side of the laser irradiation is decreased.

[0154]

Thus ,it is preferable that the laser irradiation is executed in order from the upper laser irradiation region JI at the upper side among the laser irradiation regions JI, J2, and J3 (i.e., in the order of JI, J2, and J3). Since the laser irradiation is sequentially executed from the upper laser irradiation region JI, the laser irradiation is not affected by smoke at the time of laser irradiation at the lower side.

[0155]

Further, as illustrated in FIG. 20, an airflow generation unit 35 that generates airflow in the laser irradiation region J may be disposed. The airflow generation unit 35 may be a blower such as a fan or a circulator, or may be an intake-and-exhaust system that intakes and exhausts air. As a result, the smoke 50 generated in the laser irradiation region J can be forcibly moved to the outside of the laser irradiation region J by the airflow, and the laser irradiation can be prevented from being affected by the smoke. However, it is preferable that the direction of the airflow is opposite to the moving direction of the laser irradiation position. If the direction of the airflow is the same as the moving direction of the laser irradiation position, the smoke moved by the airflow may decrease the accuracy of the laser irradiation. [0156]

In view of the above, a test was conducted to examine a preferable combination of the order of laser irradiation and the direction of airflow. FIG. 21 is a diagram illustrating a relation between an order of the laser irradiation and a direction of airflow.

[0157]

In this test, the visibility of the obtained pattern was examined under different conditions of the order of laser irradiation to the laser irradiation regions JI, J2, and J3, the presence and absence and the direction of the airflow to the laser irradiation regions JI, J2, and J3, and the presence and absence of the conveyance.

[0158]

In this test, the output of each of the laser units 5 A, 5B, and 5C was set in the range of 30 W to 70 W, and the frequency of the laser was set to an optimum value of 500 kHz to 3000 kHz. Further, an 1'0 lens having a focal length of 580 mm was used, and the scanning speed was 54 m/s, the scanning period was 12000 ms, and the frequency was 1250 kHz. The overlap ratio of the laser beam is 1.5 and the processing ratio was 70%.

[0159]

Under the conditions described above, the laser irradiation was sequentially executed on the respective laser irradiation regions JI, J2, and J3 from the downstream in the conveyance direction. In the case of conveying the container, an actual production line was assumed, and laser irradiation was executed to the containers while conveying twenty containers along a curved conveyance path at a speed of 1000 mm/s. The visibility of the pattern was evaluated FN202304987 for the pattern formed in the upper (uppermost) laser irradiation region JI that is most affected by the smoke.

[0160]

In the case of Test 1, since the laser irradiation was executed in order from the upper side without conveying the container, the smoke was less likely to affect the laser irradiation when the laser irradiation was executed to the lower side, and a good visibility value was obtained. By contrast, in the case of Test 2, the container was not conveyed as in Test 1, but since the laser irradiation was executed in order from the lower side, the visibility value was considerably decreased due to the influence of the smoke moved from the lower side during the laser irradiation at the upper side.

[0161]

In the case of Test 3, the laser irradiation was executed while the container was being conveyed. In this case, the laser irradiation was executed in order from the upper side so that the smoke was less likely to affect the laser irradiation, but the visibility was lower than the visibility in Test 1 because smoke filled the 20 containers during the laser irradiation and the containers were conveyed at a high speed. In the case of Test 4, since the laser irradiation was executed in order from the lower side while the container was being conveyed, the visibility value was further lower than the visibility in Test 3. However, in the case of Test 4, the visibility was increased as compared with the visibility in Test 2 in which the container was not conveyed. This is probably because, since the container was conveyed, the smoke was less likely to stay near the laser irradiation region.

[0162]

In the case of Test 5, the laser irradiation was executed in order from the upper side while the container 1 was being conveyed, and further, an airflow was generated from the upper side toward the lower side with respect to the laser irradiation region. As a result, the visibility was increased as compared with the visibility in Test 3 in which the airflow was generated. Further, in the case of Test 6, the visibility was further increased by directing the airflow from the lower side to the upper side that was opposite to the direction in Test 5. This is probably because, as described above, since the direction of the airflow is set to be the direction opposite to the moving direction of the laser irradiation position, the smoke is less likely to affect the laser irradiation.

[0163]

As described above, according to the test results illustrated in FIG. 21, when laser irradiation is executed to multiple laser irradiation regions JI, J2, and J3 divided in the longitudinal direction, it is preferable to execute the laser irradiation in order from the upper (uppermost) laser irradiation region, and it is also preferable to generate an airflow from the lower side toward the upper side. The laser irradiation with high accuracy can be executed because the smoke is less likely to affect the laser irradiation.

In an embodiment of the present disclosure, the laser irradiator sequentially irradiates the multiple laser irradiation region with the multiple laser beams from one of the multiple laser FN202304987 irradiation regions uppermost of the multiple laser irradiation regions downward in the intersecting direction.

[0164]

The decrease in accuracy of the laser irradiation due to smoke as described above is not limited to the case where laser irradiation is executed to the multiple laser irradiation regions JI, J2, and J3, but may also occur in the case where laser irradiation is executed to one laser irradiation region J (not divided) as illustrated in FIG. 11. Accordingly, when laser irradiation is executed to one laser irradiation region J, the airflow generation unit 35 that generates an airflow may be disposed in the laser irradiation region J to reduce the influence of smoke. In an embodiment of the present disclosure, the laser irradiation apparatus includes an airflow generator to generate airflow to a laser irradiation region on the object to be irradiated with the laser beam from the irradiator.

In an embodiment of the present disclosure, in the laser irradiation apparatus, the airflow generator generates airflow flowing upward.

[0165]

Method of Evaluating Visibility Value

A method of evaluating the visibility of a pattern will be described below. [0166]

The visibility is evaluated by capturing the image of the container and measuring the lightness of each of the visible image (pattern, image portion) and the lightness of the portion other than the image (non-image portion).

[0167]

The imaging capturing system of the container will be described with reference to FIGS. 22 to 24. FIG. 22 is a diagram illustrating an image capturing system of a container according to an embodiment of the present disclosure. FIG. 23 is a diagram illustrating the image capturing system including a white diffusing surface 54 according to an embodiment of the present disclosure. FIG. 24 is a diagram illustrating a container having an image portion 60 and a portion other than an image portion 60 (non-image portion 61) captured by the image capturing system according to an embodiment of the present disclosure. The imaging capturing system includes a container 1, a light source 51, a dark room 52, a camera 53, and a white light diffusing surface 54. The light source 51 irradiates the container 1 with a light beam, and the camera 53 captures an image of the container 1. To eliminate unnecessary images for the image capturing by the camera 53, the camera 53 captures an image in the environment of the dark room 52.

[0168]

As illustrated in FIG. 23, in the light source 51, a flat light is arranged at a predetermined angle so that the specular reflection component of the surface of the container 1 is not captured. The light source 51 is disposed at a position at which the light source 51 illuminates the container 1 with a diffused light beam. For example, the light source 51 may be disposed at a position at which the specular reflection component on the irradiation surface is not FN202304987 detected by the camera 53. The position may be, for example, a position obliquely above the container 1, or obliquely below the container 1 or on a side surface of the container 1. The white diffusion surface 54 is disposed on a side surface of the container 1 in order to reflect the influence of the contained object in the container 1 on the captured image. As a result, transmitted light from the surroundings can be considered.

[0169]

Image Capturing Conditions of Evaluation Method

The image capturing conditions were set as follows so that the white reading value is not saturated. A light-emitting diode (LED) tracer was used as the light source 51. The camera 53 was an area scan camera acA3088-57 pm manufactured by Basler Co., Ltd., and the lens of the camera 53 was Ricoh Lens FL-CC2514-2M (F1.4 f25mm 2/3"), and the image was captured by the conditions below. Image Capturing Conditions Aperture: F1.4 Exposure time: 20,000 (ps) Distance (camera to sample): 500 mm [0170]

The lightness of the image and the lightness of the portion other than the image were measured from the image captured by the image capturing system. As illustrated in FIG. 24, the lightness is converted from output values of the image portion 60 and the portion other than the image portion 60 (non-image portion 61). Although, in the output value from the camera, it is preferably that an average value of an area of about several mm² to several tens mm² is used in consideration of variations.

[0171]

In the conversion of lightness, a chart (gray chart) having a known lightness (L*) is taken by the camera 53. The lightness is converted from the image captured by the camera 53 using the G signal and the known lightness.

[0172]

G Signal and Lightness Conversion

The image captured by the camera 53 is approximated by an n-th order polynomial. For example, the G signal is converted into the lightness by the third order polynomial below. L* = Lab_lst x G1 + Lab_2nd x G2 + Lab_3rd x G3 + Lab_const Lab_lst = 0.461535

Lab_2nd = -0.000281

Lab_3rd = 0.000000

Lab_const = 1.211053

[0173]

FIG. 25 is a graph of a relation between a G signal and a lightness converted by the third order polynomial. Since the G signal and the lightness have a clear correlation and the contribution rate r2 = 0.997, there is a completely proportional relation. [0174]

Subjective Evaluation FN202304987

Subjective evaluation was conducted on the containers in which the conditions of the laser irradiation into the container 1 were changed by changing the content 6. Subjective evaluation: Scheffe's method of paired comparisons [0175]

Container: six samples with different laser processing

Content: water, coffee, and tea

Subjective evaluation: Scheffe's method of paired comparisons

Evaluator: 3 persons (The evaluations were conducted twice each)

First evaluation: water for all containers

Second evaluation: water (2 bottles), coffee (2 bottles), and tea (2 bottles) Third evaluation: water (1 bottle), coffee (3 bottles), and tea (2 bottles) Evaluation environment: office room [0176]

FIG. 26 is a graph of a relation between an image lightness L*o and a subject evaluation score. FIG. 27 is a graph of a relation between a difference (AE*) between the lightness of the image and the lightness of the portion other than the image and the subjective evaluation score. When the subjective evaluation score by the Shaeffer’s method of paired comparisons is higher, the image has a better visibility As illustrated in the regions enclosed by the dashed lines in FIGS. 26 and 27, there are containers having poor correlation. In these containers, the lightness (E*o) of the image is significantly lower, the lightness difference (AL*) is smaller, or both.

[0177]

In order to obtain a mathematical expression with higher correlation with respect to such a container, the seventh mathematical expression below was derived by multiplying the lightness L*o of the image by (1-exp (AL*)). As illustrated in FIG. 28, since Y = (1-exp (— x)) approaches Y = 0 as x decreases, the seventh mathematical expression expresses a tendency that the visibility decreases as the lightness difference (AL*) decreases. [0178]

Accordingly, the visibility value is expressed by the seventh mathematical expression below. [0179]

Seventh Mathematical Expression

Visibility Value = b₀- Lg’ (1 — exp (b₅ « AL* ) )

[0180] where L*o represents the lightness of an image, AL* represents the difference between the lightness of an image and the lightness of a portion other than the image, bo is a positive real number and is preferably around 0.2, and bl is a negative real number, and preferably around -0.2. The visibility value expressed by the seventh mathematical expression represents a feature that the visibility is higher as the lightness of an image is higher, and the visibility is lost when the lightness difference from the portion other than the image is eliminated. FN202304987

[0181]

The visibility value represented by the seventh mathematical expression calculated with bo = 0.195 and bi = -0.193 has a higher correlation (R2 = 0.943) with the subjective evaluation score (the Shaeffer’s method of paired comparisons) when the processing conditions and the content 6 contained in the container 1 are changed as illustrated in FIG. 29. The evaluation is conducted by the visibility value calculated in this way.

[0182]

Subjective Evaluation Method

With respect to a container in which an image (character) was laser-processed under the conditions below, a subjective evaluation of the image was conducted, and the visibility was evaluated in five-grade evaluation. FIG. 30 is a graph illustrating a relation between the subject evaluation score and the visibility value. Evaluation Condition Evaluator: 30 persons Containers: 10 samples having characters of 5.5 point (pt) formed under various conditions of the laser processing and including various contents (e.g., water or tea) Evaluation environment: typical office room Evaluation method: The evaluators conduct the subjective evaluation according to the five-grade evaluation (evaluation ranks) below. Evaluation Ranks 1: Unreadable 2: Less readable 3: Thin image 4: More readable

5: Clear image which is not a problem as a commercial product [0183]

According to the results in FIG. 30, although there were slight variations due to the subjective evaluation, the average value was equal to or higher than the evaluation rank 3 in which the characters are readable when the visibility value is 2 or higher. In addition, it was found that the visibility value of 7.0 or more was rated as 5 (clear image without any problem as a commercial product) in all evaluators. [0184]

Although the embodiments have been described above, the embodiments of the present disclosure are not limited to the configurations described above. The embodiments of the present disclosure may be modified without departing from the scope or spirit of the disclosure and may be determined appropriately in accordance with applications. [0185]

In an embodiment of the present disclosure described above, the laser irradiation apparatus 100 is disposed outside the center O (on the side opposite to the center O) of the curved conveyance path 20 (the conveyance path circle K). However, an embodiment of the present disclosure is not limited to the laser irradiation apparatus 100 having such a positional relation with respect to the curved conveyance path 20, and is also applicable to a laser irradiation system 1000B including a laser irradiation apparatus 100B disposed on the inner side (center O side) of the conveyance path 20 with respect to the center O as illustrated in FIG. 31. FN202304987

[0186]

In a configuration illustrated in FIG. 31, the laser irradiation apparatus 100B sequentially irradiates the container 1 with the laser beam L from the downstream position (laser irradiation start point al) on the container 1 in the conveyance direction F, and then irradiates the upstream position on the container 1 with the laser beam L. As a result, the accuracy of the laser irradiation on the container 1 can be increased as same with the above-described embodiment.

[0187]

Also in this case, the position of the emission point Q at which the laser is emitted from the deflector 13 is preferably on a straight line M passing through the center position B (the center position in the position (2)) of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13 and the center O of the conveyance path circle K, or within a range of less than ±5° (angle P) in the circumferential direction with the center B of the container 1 when the container 1 comes closest to the emission point Q of the deflector 13 as the center with the straight line M as a reference.

[0188]

The laser irradiation apparatus according to an embodiment of the present disclosure is not limited to the case where the object (container 1) is conveyed along the conveyance path 20 having a circular path, but is also applicable to the case where the object is conveyed along a conveyance path having a curved shape other than the circular shape such as an elliptical shape.

[0189]

Aspects of the present disclosure include at least a drying apparatus, a drying method, and a molding system having the following configurations.

[0190]

First Aspect

A laser irradiation apparatus irradiates an object to be conveyed along a curved conveyance path with a laser beam. The object is irradiated with the laser beam from a downstream position of the object in a conveyance direction of the object, and then irradiated with the laser beam to an upstream position of the object in the conveyance direction.

[0191]

Second Aspect

In the laser irradiation apparatus according to the first aspect, the laser irradiation apparatus irradiates a laser irradiation start position of the object with the laser beam in a direction intersecting the conveyance direction of the object, shifts a laser irradiation position to the a position upstream from the laser irradiation start position in the conveyance direction, and irradiates the object with the laser beam in the direction intersecting the conveyance direction of the object.

[0192]

Third Aspect FN202304987

The laser irradiation apparatus according to the first or second aspect includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam oscillated from the laser oscillator. As viewed from a direction perpendicular to a plane including a conveyance path circle disposed along the conveyance path, a mathematical expression below is satisfied, R (1 - cos 61) + r (1 - cos (62 - 91)) < 2 DoF, where 91 is an angle AOB that connects three points A, O, and B, where A is a center position of the object at a time when a laser irradiation to the object starts, O is a center of the conveyance path circle, and B is a center position of the object at which the object comes closest to an emission point of the deflector that emits the laser beam, 62 is an angle al -A-cl that connects three points al, A, and cl, where al is a laser irradiation start point on the object, A is the center of the object, and cl is a front position of the object, R is a radius of the conveyance path circle, r is a radius of the object, and DoF is a depth of a focus of the laser beam.

[0193]

Fourth Aspect

The laser irradiation apparatus according to any one of the first to third aspects includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam oscillated from the laser oscillator. As viewed from a direction perpendicular to a plane including a conveyance path circle disposed along the conveyance path, a straight line direction passing a center of the conveyance path circle and a front position of the object at which the object comes closest to an emission point of the deflector that emits the laser beam is a Y-axis direction, an intermediate position in the Y-axis direction between a laser irradiation start point of the object at a time when the laser irradiation to the object starts and the front position of the object at which the object comes closes to the emission point is a best focus position of the laser beam.

[0194]

Fifth Aspect

The laser irradiation apparatus according to any one of the first to fourth aspects includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam oscillated from the laser oscillator. As viewed from a direction perpendicular to a plane including a conveyance path circle disposed along the conveyance path, an emission point of a deflector is disposed in a straight line passing a center position of the object at which the object comes closest to the emission point of the deflector to emit a laser beam and a center of the conveyance path circle.

[0195]

Sixth Aspect

The laser irradiation apparatus according to any one of the first to fourth aspects includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam oscillated from the laser oscillator. As viewed from a direction perpendicular to a plane including a conveyance path circle disposed along the conveyance path, an emission point of the deflector FN202304987 to emit a laser beam is disposed in a range larger than - 5 degrees and less than +5 degrees in a circumferential direction with respect to a center position of the object at which the object comes closest to the emission point of the deflector based on a straight line passing a center position of the object at which the object comes closest to the emission point of the deflector and a center of the conveyance path circle.

[0196]

Seventh Aspect

The laser irradiation apparatus according to any one of the first to sixth aspects comprising multiple oscillation sources to emit respective laser beams, the object includes a laser irradiation region including multiple laser irradiation regions different from each other and divided in a direction intersecting the conveyance direction of the object, and the multiple laser irradiation regions are irradiated with the respective laser beams emitted from the multiple laser oscillators.

[0197]

Eighth Aspect

In the laser irradiation apparatus according to the seventh aspect, the object is sequentially irradiated with a laser beam from a laser irradiation region disposed upward among the multiple laser irradiation regions different from each other and divided.

[0198]

Ninth Aspect

In the laser irradiation apparatus according to any one of the first to eighth aspects includes an airflow generation unit to generate airflow to a laser irradiation region of the object.

[0199]

Tenth Aspect

In the laser irradiation apparatus according to the ninth aspect, the airflow generation unit generates airflow upward.

[0200]

Eleventh Aspect

A laser irradiation method includes irradiating an object to be conveyed along a curved conveyance path with a laser beam from a downstream position of the object in a conveyance direction of the object and irradiating the object with the laser beam to an upstream position of the object.

[0201]

Twelfth Aspect

A laser irradiation system includes a conveyance apparatus to convey an object along a curved conveyance path and the laser irradiation apparatus to irradiate the object with a laser beam from a downstream position of the object in the conveyance direction of the object and irradiating an upstream position of the object with a laser beam.

[0202]

Thirteenth Aspect FN202304987

Fourteenth Aspect

In the laser irradiation apparatus according to the thirteenth aspect, the laser irradiation apparatus starts irradiating the object with the laser beam moving from the downstream position on the object in a first intersecting direction intersecting the conveyance direction, shifts an irradiation position of the laser beam to another position upstream from the downstream position in the conveyance direction, and irradiates the object with the laser beam moving from said another position in a second intersection direction opposite to the first intersecting direction.

Fifteenth Aspect

In the laser irradiation apparatus according to the thirteenth or fourteenth aspect, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An expression below is satisfied in a plane of the curved conveyance path having a shape of circle, R (1 - cos e 1) + r (1 - cos (62 - 91)) < 2xDoF, where

91 is an angle AOB that connects three points A, O, and B, where:

62 is an angle al-A-cl that connects three points al, A, and cl, where al is the downstream position on the object, A is the center position of the object, cl is a front position of the object to be faced with the deflector,

R is a radius of the curved conveyance path, r is a radius of the object, and

DoF is a depth of a focus of the laser beam.

Sixteenth Aspect

In the laser irradiation apparatus according to any one of the thirteenth to fifteenth aspects, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An intermediate position in a Y-axis direction, between the downstream position on the object at a start of a laser irradiation and a front position of the object at which the object comes closest to an emission point of the deflector, is a best focus position of the laser beam in a plane of the curved conveyance path having a shape of circle. The Y-axis direction is a straight line passing a center of the conveyance path in the plane and FN202304987 the front position of the object.

Seventeenth Aspect

In the laser irradiation apparatus according to any one of the thirteenth to sixteenth aspects, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An emission point of the deflector is in a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle.

Eighteenth Aspect

In the laser irradiation apparatus according to any one of the thirteenth to sixteenth aspects, the irradiator includes a laser oscillator to oscillate a laser beam and a deflector to deflect the laser beam emitted from the laser oscillator. An emission point of the deflector is in a range greater than -5 degrees and smaller than +5 degrees from a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle in a circumferential direction of the object around the center position of the object.

Nineteenth Aspect

In the laser irradiation apparatus according to any one of the thirteenth aspect to eighteenth aspects, the irradiator includes multiple laser oscillators to respectively oscillate multiple laser beams, and the multiple laser oscillators respectively irradiate multiple laser irradiation regions, divided in an intersecting direction intersecting the conveyance direction, on the object with the multiple laser beams.

Twentieth Aspect

In the laser irradiation apparatus according to the nineteenth aspect, the laser irradiator sequentially irradiates the multiple laser irradiation region with the multiple laser beams from one of the multiple laser irradiation regions uppermost of the multiple laser irradiation regions downward in the intersecting direction.

Twenty-first Aspect

The laser irradiation apparatus according to any one of the thirteenth aspect to twentieth aspects includes an airflow generator to generate airflow to a laser irradiation region on the object to be irradiated with the laser beam from the irradiator.

Twenty-second Aspect

The laser irradiation apparatus according to any one of the twenty-first aspect, the airflow generator generates airflow flowing upward.

Twenty-third Aspect

A laser irradiation method including starting an irradiation to an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction of the object; and ending the irradiation to the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction. FN202304987

Twenty-fourth Aspect

A laser irradiation system includes a conveyor having a curved conveyance path to convey an object along the curved conveyance path in a conveyance direction and the laser irradiation apparatus according to the first or second aspect. The laser irradiation apparatus starts irradiating the object conveyed along the curved conveyance path in the conveyance direction with a laser beam from a downstream position on the object in the conveyance direction and ends irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

[0203]

The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above .

[0204]

The present invention can be implemented in any convenient form, for example using dedicated hardware, or a mixture of dedicated hardware and software. The present invention may be implemented as computer software implemented by one or more networked processing apparatuses. The processing apparatuses include any suitably programmed apparatuses such as a general purpose computer, a personal digital assistant, a Wireless Application Protocol (WAP) or third-generation (3G)-compliant mobile telephone, and so on. Since the present invention can be implemented as software, each and every aspect of the present invention thus encompasses computer software implementable on a programmable device. The computer software can be provided to the programmable device using any conventional carrier medium (carrier means). The carrier medium includes a transient carrier medium such as an electrical, optical, microwave, acoustic or radio frequency signal carrying the computer code. An example of such a transient medium is a Transmission Control Protocol/Intemet Protocol (TCP/IP) signal carrying computer code over an IP network, such as the Internet. The carrier medium also includes a storage medium for storing processor readable code such as a floppy disk, a hard disk, a compact disc read-only memory (CD- ROM), a magnetic tape device, or a solid state memory device.

[0205]

Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions. [0206] FN202304987

This patent application is based on and claims priority to Japanese Patent Application No. 2023-038703, filed on March 13, 2023, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

[Reference Signs List]

[0207]

I Container (Object)

I I Laser oscillator

13 Deflector

20 Conveyance path

35: Airflow generation unit

100 Laser irradiation apparatus

200 Conveyance apparatus

1000 Laser irradiation system al Laser irradiation start point b3 Laser irradiation end point

F Conveyance direction (conveyance direction of the object)

K Conveyance path circle

N Best focus position

Claims

FN202304987 [CLAIMS]

[Claim 1]

A laser irradiation apparatus comprising: an irradiator to: start irradiating an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction; and end irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

[Claim 2]

The laser irradiation apparatus according to claim 1, wherein the laser irradiation apparatus: starts irradiating the object with the laser beam moving from the downstream position on the object in a first intersecting direction intersecting the conveyance direction; shifts an irradiation position of the laser beam to another position upstream from the downstream position in the conveyance direction; and irradiates the object with the laser beam moving from said another position in a second intersection direction opposite to the first intersecting direction.

[Claim 3]

The laser irradiation apparatus according to claim 1 or 2, wherein the irradiator includes: a laser oscillator to oscillate a laser beam; and a deflector to deflect the laser beam emitted from the laser oscillator, wherein an expression below is satisfied in a plane of the curved conveyance path having a shape of circle,

91 is an angle AOB that connects three points A, O, and B, where:

A is a center position of the object at a start of a laser irradiation;

O is a center of the curved conveyance path in the plane; and

62 is an angle al-A-cl that connects three points al, A, and cl, where al is the downstream position on the object,

A is the center position of the object, cl is a front position of the object to be faced with the deflector,

R is a radius of the curved conveyance path, r is a radius of the object, and

DoF is a depth of a focus of the laser beam.

[Claim 4]

The laser irradiation apparatus according to claim 1 or 2, FN202304987 wherein the irradiator includes: a laser oscillator to oscillate a laser beam; and a deflector to deflect the laser beam emitted from the laser oscillator, wherein an intermediate position in a Y-axis direction, between the downstream position on the object at a start of a laser irradiation and a front position of the object at which the object comes closest to an emission point of the deflector, is a best focus position of the laser beam in a plane of the curved conveyance path having a shape of circle, where the Y-axis direction is a straight line passing a center of the conveyance path in the plane and the front position of the object.

[Claim 5]

The laser irradiation apparatus according to claim 1 or 2, wherein the irradiator includes: a laser oscillator to oscillate a laser beam; and a deflector to deflect the laser beam emitted from the laser oscillator, wherein an emission point of the deflector is in a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle.

[Claim 6]

The laser irradiation apparatus according to claim 1 or 2, wherein the irradiator includes: a laser oscillator to oscillate a laser beam; and a deflector to deflect the laser beam emitted from the laser oscillator, wherein an emission point of the deflector is in a range greater than -5 degrees and smaller than +5 degrees from a straight line passing a center position of the object at which the object comes closest to an emission point of the deflector and a center of the conveyance path in a plane of the curved conveyance path having a shape of circle in a circumferential direction of the object around the center position of the object.

[Claim 7]

The laser irradiation apparatus according to claim 1 or 2, wherein the irradiator includes multiple laser oscillators to respectively oscillate multiple laser beams, and the multiple laser oscillators respectively irradiate multiple laser irradiation regions, divided in an intersecting direction intersecting the conveyance direction, on the object with the multiple laser beams.

[Claim 8]

The laser irradiation apparatus according to claim 7, wherein the laser irradiator sequentially irradiates the multiple laser irradiation region with the multiple laser beams from one of the multiple laser irradiation regions uppermost of the multiple laser irradiation regions downward in the intersecting direction.

[Claim 9] FN202304987

The laser irradiation apparatus according to claim 8 includes an airflow generator to generate airflow to a laser irradiation region on the object to be irradiated with the laser beam from the irradiator.

[Claim 10]

The laser irradiation apparatus according to claim 9, wherein the airflow generator generates airflow flowing upward.

[Claim 11]

A laser irradiation method comprising: starting an irradiation to an object conveyed along a curved conveyance path in a conveyance direction with a laser beam from a downstream position on the object in the conveyance direction of the object; and ending the irradiation to the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.

[Claim 12]

A laser irradiation system comprising: a conveyor having a curved conveyance path to convey an object along the curved conveyance path in a conveyance direction; and the laser irradiation apparatus according to claim 1 or 2, wherein the laser irradiation apparatus starts irradiating the object conveyed along the curved conveyance path in the conveyance direction with a laser beam from a downstream position on the object in the conveyance direction; and ends irradiating the object with the laser beam at an upstream position upstream from the downstream position on the object in the conveyance direction.