LASER PROCESSING METHOD FOR LONG FILM

Abstract

A laser processing method for a long film is disclosed which has high productivity. A laser processing method according to the present invention includes a process of cutting a long film F by irradiating the long film F with a laser beam L while scanning the laser beam L by a deflecting operation of a galvanometer scanner 13 and while continuously conveying the long film F in the longitudinal direction. The control device 3 controls the deflecting operation of the galvanometer scanner 13 based on a desired cutting shape of the long film F set in advance and a conveying speed of the long film F that is calculated using a rotary encoder 2.

Claims

1. A laser processing method for a long film, comprising: a process of cutting a long film by irradiating the long film with a laser beam while scanning the laser beam by a deflecting operation of a galvanometer scanner and while continuously conveying the long film in a longitudinal direction, wherein the deflecting operation of the galvanometer scanner is controlled based on a desired cutting shape of the long film set in advance and a conveying speed of the long film.

2. The laser processing method for a long film according to claim 1, wherein: a conveying speed of the long film is measured, and the deflecting operation of the galvanometer scanner is controlled based on the desired cutting shape of the long film and the measured conveying speed of the long film.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is a perspective view that schematically illustrates an example of an arrangement state of a laser processing apparatus that is used in a laser processing method according to one embodiment of the present invention.

[0027] FIG. 2 is a plan view that schematically illustrates an internal configuration of an optical unit of the laser processing apparatus illustrated in FIG. 1.

[0028] FIG. 3 is views that illustrate outline flows of a single cycle of laser processing methods according to an Example, Comparative Examples and a Reference Example.

[0029] FIG. 4 is a table showing results of evaluating the cycle times of the laser processing methods according to the Example, the Comparative Examples and the Reference Example.

DESCRIPTION OF EMBODIMENT

[0030] Hereunder, a laser processing method for a long film according to one embodiment of the present invention is described with reference being made as appropriate to the attached drawings.

[0031] FIG. 1 is a perspective view that schematically illustrates an example of an arrangement state of a laser processing apparatus used in a laser processing method according to one embodiment of the present invention. FIG. 2 is a plan view that schematically illustrates an internal configuration of an optical unit of the laser processing apparatus illustrated in FIG. 1. Note that, in FIG. 1 and FIG. 2, an arrow mark X represents a width direction of a long film F (direction orthogonal to a longitudinal direction in a plane of the long film F), an arrow mark Y represents the longitudinal direction of the long film F (conveyance direction), and an arrow mark Z represents a direction of the normal line to the long film F.

[0032] As illustrated in FIG. 1, a laser processing apparatus 100 of the present embodiment includes an optical unit 1, a rotary encoder 2 and a control device 3.

[0033] As illustrated in FIG. 2, the optical unit 1 includes a laser beam source 11, an optical element 12 and a galvanometer scanner 13. Specifically the laser beam source 11, the optical element 12 and the galvanometer scanner 13 are contained inside a housing of the optical unit 1 illustrated in FIG. 1.

[0034] For example, a laser beam source that pulses a laser beam L having a wavelength in the infrared region is used as the laser beam source 11. Preferably, a CO laser beam source (oscillation wavelength: 5 m) or a CO.sub.2 laser beam source (oscillation wavelength: 9.3 to 10.6 m) is used for which the wavelength of the laser beam L that is pulsed from the laser beam source 11 is 5 m or more and 11 m or less. In the case of using a CO laser beam source, an optical path of the laser beam L may be purged using an inert gas such as nitrogen.

[0035] The optical element 12 is constituted by various optical components such as an acousto-optic modulator (AOM) for controlling the power (intensity) of the laser beam L, an expander for adjusting the beam size of the laser beam L, and a homogenizer for flattening the spatial beam profile of the laser beam L.

[0036] The laser beam L that is oscillated from the laser beam source 11 and passes through the optical element 12 is reflected and deflected by the galvanometer scanner 13 and impinges onto the long film F. Specifically, an opening (not illustrated) is provided in the undersurface of the housing of the optical unit 1 illustrated in FIG. 1, and the laser beam L reflected and deflected by the galvanometer scanner 13 is impinges onto the long film F through the aforementioned opening.

[0037] The galvanometer scanner 13 of the present embodiment includes a movable lens 131, a condenser lens 132, a first galvanometer mirror 133 and a second galvanometer mirror 134.

[0038] The movable lens 131 is a lens capable of changing position in the optical axis direction of the laser beam L (in the example illustrated in FIG. 2, the X-direction that is the width direction of the long film F). When the movable lens 131 changes position, the focal position of the laser beam L that is condensed by the condenser lens 132 changes.

[0039] The first galvanometer mirror 133 includes a mirror part 133a and a galvanometer motor 133b. The mirror part 133a pivots about the direction of the normal line (Z direction) to the long film F by means of the galvanometer motor 133b. The second galvanometer mirror 134 includes a mirror part 134a and a galvanometer motor 134b. The mirror part 134a pivots about the width direction (X-direction) of the long film F by means of the galvanometer motor 134b.

[0040] After the laser beam L incident on the galvanometer scanner 13 passes through the movable lens 131 and the condenser lens 132, the laser beam L is reflected and deflected in sequence at the mirror part 133a of the first galvanometer mirror 133 and the mirror part 134a of the second galvanometer mirror 134 and impinges onto the long film F. Because the mirror part 133a of the first galvanometer mirror 133 and the mirror part 134a of the second galvanometer mirror 134 pivot as mentioned above, the deflection direction of the laser beam L successively changes according to the pivot angles of the mirror part 133a and the mirror part 134a, and the laser beam L is thus scanned on the long film F (on an X-Y two-dimensional plane formed from the width direction (X-direction) and the longitudinal direction (Y-direction) of the long film F). At such time, the movable lens 131 is controlled so as to change position according to the pivot angles of the mirror part 133a and the mirror part 134a so that the spot diameter of the laser beam L is a uniform diameter at each of the scanning positions of the laser beam L.

[0041] If the irradiation direction of the laser beam L that is scanned and emitted to the long film F by the galvanometer scanner 13 deviates from the direction of the normal line to the long film F (if the laser beam L is emitted at an angle relative to the direction of the normal line to the long film F), the cut end face of the long film F will be a tapered shape. In order to suppress the occurrence of a situation in which the cut end face becomes an excessively tapered shape, it is preferable to control the deflecting operation of the galvanometer scanner 13 so that the angle of incidence of the laser beam L (angle formed between the irradiation direction of the laser beam L and the direction of the normal line to the long film F) becomes 20 or less, and further preferably is made 15 or less.

[0042] Note that, it is also possible to use a commercially available apparatus such as, for example, 3D Galvanometer Scanner manufactured by Raylase GmbH, Laser Scanning System manufactured by Scanlab GmbH, Galvanometer Scanner System manufactured by Y-E Data Inc., or Galvanometer Scanner System manufactured by Arges GmbH as the galvanometer scanner 13 which is equipped with the movable lens 131, the condenser lens 132, the first galvanometer mirror 133 and the second galvanometer mirror 134 as in the present embodiment.

[0043] Furthermore, it is also possible to use a galvanometer scanner which is equipped with the condenser lens 132, the first galvanometer mirror 133 and the second galvanometer mirror 134 (and which is not equipped with the movable lens 131) instead of the galvanometer scanner 13 of the present embodiment. It is possible to use a commercially available apparatus such as, for example, 2D Galvanometer Scanner manufactured by Raylase GmbH, as the aforementioned galvanometer scanner. In the case of using a galvanometer scanner which is not equipped with the movable lens 131, preferably a telecentric f lens is disposed along the optical path of the laser beam L between the galvanometer scanner and the long film F. The laser beam L incident from the galvanometer scanner which is not equipped with the movable lens 131 and exits from the telecentric f lens will impinge onto the long film F from the direction of the normal line to the long film F at each of the scanning positions on the long film F, and will also impinge with a uniform spot diameter at each of the scanning positions.

[0044] In a case where the dimension in the width direction (X-direction) of the long film is small (for example, the dimension in the width direction is 60 mm), it is preferable to use a galvanometer scanner which is not equipped with the movable lens 131, and a telecentric f lens. The reason is that, since the long film F will be irradiated with the laser beam from the direction of the normal line to the long film F at each of the scanning positions, fluctuations in the spot diameter (spot diameter along the surface of the long film F) will not arise due to irradiation that is inclined relative to the direction of the normal line. On the other hand, in a case where the dimension in the width direction (X-direction) of the long film is large (for example, the dimension in the width direction is >60 mm), since use of a telecentric f lens will not be practical, it is preferable to use the galvanometer scanner 13 equipped with the movable lens 131 as in the present embodiment. In a case where long films F whose width direction dimensions differ significantly from each other are to be conveyed on the same conveyance line, it is also conceivable to provide both a laser processing apparatus that uses a telecentric f lens and a galvanometer scanner without the movable lens 131, and the laser processing apparatus 100 that uses the galvanometer scanner 13 equipped with the movable lens 131 as in the present embodiment.

[0045] The rotary encoder 2 is, for example, attached to a rotary shaft of a conveying roll R1 that conveys the long film F, and detects the rotational position of the conveying roll R1 and successively outputs the detected rotational position to the control device 3.

[0046] The control device 3 controls the deflecting operation of the galvanometer scanner 13. Specifically, the desired cutting shape of the long film F is input in advance to the control device 3. Further, as mentioned above, the rotational position of the conveying roll R1 is successively input to the control device 3, and the control device 3 calculates the peripheral speed of the conveying roll R1 by means of the rotational speed that is calculated based on the rotational positions that are input and the diameter of the conveying roll R1, and treats the calculated peripheral speed of the conveying roll R1 as the conveying speed of the long film F. The control device 3 controls the deflecting operation of the galvanometer scanner 13 based on the input desired cutting shape of the long film F and the calculated conveying speed of the long film F. Specifically, the control device 3 controls the deflecting operation of the galvanometer scanner 13 so that the scanning positions of the laser beam L on the long film F that are determined based on the resultant speed of the scanning speed of the laser beam L which is scanned by the deflecting operation of the galvanometer scanner 13 and the conveying speed of the long film F match the desired cutting shape of the long film F (desired cutting positions). The control device 3 outputs a control signal for performing the aforementioned control to the galvanometer motor 133b of the first galvanometer mirror 133 and the galvanometer motor 134b of the second galvanometer mirror 134. Further, the control device 3 outputs a control signal for causing the movable lens 131 to change position in accordance with the pivot angles of the mirror part 133a and the mirror part 134a to a drive mechanism (not illustrated) for causing the movable lens 131 to change position, so that the spot diameter of the laser beam L is a uniform diameter at each of the scanning positions of the laser beam L.

[0047] Further, the control device 3 outputs a control signal to the laser beam source 11 to control settings with respect to the on/off timing, repetition frequency, and power of the laser beam L that is oscillated from the laser beam source 11.

[0048] A laser processing method according to the present embodiment that uses the laser processing apparatus 100 having the above configuration is described hereunder.

[0049] As illustrated in FIG. 1, the laser processing method according to the present embodiment includes a process of cutting the long film F by irradiating the long film F with the laser beam L while scanning the laser beam L by means of a deflecting operation of the galvanometer scanner 13 and while continuously conveying the long film F in the longitudinal direction (Y-direction) between the conveying rolls R1 and R2. At such time, in order to make the tensile force of the long film F between the conveying rolls R1 and R2 a certain magnitude or more, it is preferable to set the rotational speed of the conveying roll R1 located on the downstream side in the conveyance direction to be somewhat higher than the rotational speed of the conveying roll R2 located on the upstream side in the conveyance direction. Further, to suppress the occurrence of a disturbance such as flapping during conveyance of the long film F and thereby perform stable cutting, a suction device for sucking the long film F to an extent to which continuous conveyance is possible may be provided. Further, at such time, the control device 3 controls the deflecting operation of the galvanometer scanner 13 based on the desired cutting shape of the long film F set in advance and the conveying speed of the long film F (in the present embodiment, a conveying speed calculated using a rotational position detected by the rotary encoder 2). The cutting form with respect to the long film F is not limited to a full cut, and it is also possible to adopt a half cut as the cutting form.

[0050] Examples of the long film F that is the cutting object in the laser processing method according to the present include a plastic film. Examples of the plastic film include a single-layer film or a laminated film composed of multiple layers which is formed of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), an acrylic resin such as polymethyl methacrylate (PMMA), a cyclic olefin polymer (COP), a cyclic olefin copolymer (COC), a polycarbonate (PC), a urethane resin, a polyvinyl alcohol (PVA), a polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polystyrene (PS), triacetylcellulose (TAC), polyethylene naphthalate (PEN), ethylene vinyl acetate (EVA), a polyamide (PA), a silicone resin, an epoxy resin, a liquid crystal polymer, or a plastic material such as various kinds of resin foam.

[0051] The long film F adopted as the cutting object in the laser processing method according to the present embodiment preferably has an absorptivity of 15% or more with respect to the wavelength of the laser beam L with which it is irradiated.

[0052] In a case where the plastic film is a laminated film composed of multiple layers, various kinds of adhesive such as acrylic adhesive, urethane adhesive, or silicone adhesive, or a bonding agent may be interposed between the layers.

[0053] Further, an electroconductive inorganic membrane composed of indium tin oxide (ITO), Ag, Au, or Cu or the like may be formed on the surface of the plastic film.

[0054] The laser processing method according to the present embodiment is favorably used for various kinds of optical films such as a polarizing film or a phase contrast film to be particularly used in a display.

[0055] The thickness of the long film F is preferably made to fall within the range of 20 to 500 m.

[0056] In the laser processing method according to the present embodiment, the control device 3 controls the galvanometer scanner 13 so that a shot pitch of the laser beam L is smaller than the spot diameter on the long film F of the laser beam L. The shot pitch is a value obtained by dividing the scanning speed of the laser beam L (relative movement speed between the laser beam L and the long film F) by the repetition frequency (equivalent to the number of pulses of the oscillated laser beam L per unit time), and means the interval between a laser beam L emitted by a certain pulsing and a laser beam L emitted by the next pulsing.

[0057] Note that, in the laser processing method according to the present embodiment, there is also a possibility that, when the long film F is conveyed in the longitudinal direction (Y-direction) between the conveying rolls R1 and R2, the long film F will zigzag in the width direction (X-direction). To suppress the influence of such zigzagging, it suffices to provide a sensor that detects an edge of the long film F (for example, an optical or ultrasound sensor), and to successively input the edge position of the long film F detected by the sensor into the control device 3, and to control the deflecting operation of the galvanometer scanner 13 by means of the control device 3 by also using the input edge position. Specifically, it suffices for the control device 3 to control the deflecting operation of the galvanometer scanner 13 so that the scanning positions of the laser beam L on the long film F that are determined based on a resultant speed of the scanning speed of the laser beam L by the deflecting operation of the galvanometer scanner 13 and the conveying speed of the long film F and the edge position of the long film F, match the desired cutting shape (desired cutting positions) of the long film F.

[0058] Hereunder, an example of results obtained when the productivity of laser processing methods according to the present embodiment (Example), Comparative Examples and a Reference Example were evaluated will be described.

[0059] When evaluating the productivity, with respect to each of the laser processing methods, 6 sheets of optical films, each of which is for a smartphone and has an approximately rectangular shape in which the dimensions of the film prior to cutting were 130 mm in the width direction (X-direction) and 70 mm in the longitudinal direction (Y-direction), were cut out per cycle, and the cycle times for cases in which the respective laser processing method were applied were calculated.

[0060] FIG. 3 is views that illustrate outline flows of one cycle of the laser processing methods according to the Example, the Comparative Examples and the Reference Example. FIG. 3(a) illustrates the flow of one cycle of a laser processing method according to the Example. FIG. 3(b) illustrates the flow of one cycle of a laser processing method according to a Comparative Example 1. FIG. 3(c) illustrates the flow of one cycle of a laser processing method according to a Comparative Example 2. FIG. 3(d) illustrates the flow of one cycle of a laser processing method according to the Reference Example.

[0061] As illustrated in FIG. 3(a), in the laser processing method according to the Example, as described above, a long film F was cut by irradiating the long film F with the laser beam L while scanning the laser beam L by a deflecting operation of the galvanometer scanner 13 while continuously conveying the long film F between the conveying rolls R1 and R2.

[0062] As illustrated in FIG. 3(b), in the laser processing method according to the Comparative Example 1, a sheet-like film was placed on an X-Y dual-axis stage and fixed by suction thereto, and the film was cut by changing the relative position on an X-Y two-dimensional plane of the film with respect to the laser beam L by driving the X-Y dual-axis stage and irradiating the film with the laser beam L while scanning the laser beam L by a deflecting operation of the galvanometer scanner 13 in a similar manner to the Example.

[0063] As illustrated in FIG. 3(c), in the laser processing method according to the Comparative Example 2, a long film F was cut by intermittently conveying the long film F between conveying rolls R1 and R2 and, in a similar manner to the method disclosed in Patent Literature 1, placing the long film F in a state in which the long film F was fixed by suction at a position at which the long film F stopped, and irradiating the long film F with the laser beam L while scanning the laser beam L by a deflecting operation of the galvanometer scanner 13.

[0064] As illustrated in FIG. 3(d), in the laser processing method according to the Reference Example, although a long film F was intermittently conveyed similarly to the laser processing method according to the Comparative Example 2, fixing of the long film F by suction was not performed at a position at which the long film F was stopped, and the long film F was cut by irradiating the long film F with the laser beam L while scanning the laser beam L by a deflecting operation of the galvanometer scanner 13.

[0065] FIG. 4 is a table showing results of evaluating the cycle times of the laser processing methods according to the Example, the Comparative Examples and the Reference Example.

[0066] As illustrated in FIG. 4, in the laser processing method according to the Comparative Example 1, time (4 sec in the example shown in FIG. 4) was required to place the sheet-like film at a predetermined position on the X-Y dual-axis stage, and time (4 sec in the example shown in FIG. 4) was required to take the film off the X-Y dual-axis stage to retrieve the film after laser processing. Further, time (0.3 sec in the example shown in FIG. 4) was required to fix the sheet-like film by suction to the X-Y dual-axis stage, and time (0.3 sec in the example shown in FIG. 4) was required to release the fixing by suction of the film. In addition, in the laser processing method according to the Comparative Example 1, because the X-Y dual-axis stage was being driven when scanning the laser beam L, the time required for laser processing (7.8 sec in the example shown in FIG. 4) was longer in comparison to the cases of scanning the laser beam L by only a deflecting operation of the galvanometer scanner 13 (in the Comparative Example 2, the Reference Example, and the Example).

[0067] As illustrated in FIG. 4, in the laser processing method according to the Comparative Example 2, because the long film F was conveyed between the conveying rolls R1 and R2, in comparison to a case of using a sheet-like film as in the laser processing method according to the Comparative Example 1, time was not required to place the film on an X-Y dual-axis stage and take the film off therefrom.

[0068] However, because intermittent conveyance was used in which conveying and stopping of the long film F were alternately repeated, it took more time to convey the long film F (1.8 sec in the example shown in FIG. 4) in comparison to a case of continuously conveying the long film F without causing the long film F to stop. Further, similarly to the laser processing method according to the Comparative Example 1, time was required to fix the long film F by suction (1.8 sec in the example shown in FIG. 4), and time was also required to release the long film F fixed by suction (1.8 sec in the example shown in FIG. 4).

[0069] As illustrated in FIG. 4, in the laser processing method according to the Reference Example, unlike the laser processing method according to the Comparative Example 2, since fixing of the long film F by suction at the stopped position was not performed, time was not required to fix the long film F by suction and time was not required to release fixing by suction of the long film F.

[0070] However, similarly to the laser processing method according to the Comparative Example 2, because the long film F was intermittently conveyed, it took more time to convey the long film F (1.8 sec in the example shown in FIG. 4) in comparison to a case of continuously conveying the long film F without stopping.

[0071] As illustrated in FIG. 4, in the laser processing method according to the Example, unlike the laser processing method according to the Reference Example, because the laser beam L was scanned by a deflecting operation of the galvanometer scanner 13 while continuously conveying the long film F between the conveying rolls R1 and R2, the conveying time of the long film F was shortened (time necessary for stopping operations and resuming the conveying operation was not required) in comparison to the laser processing method according to the Reference Example.

[0072] As illustrated in FIG. 4, when productivity was evaluated based on the cycle times calculated for the Comparative Example 1, the Comparative Example 2, the Reference Example and the Example, it was found that, when the laser processing method according to the Comparative Example 1 was adopted as a reference (productivity=1.0), the productivity of the laser processing method according to the Example was 6.3, indicating that the productivity increased by a large margin.

[0073] As described above, according to the laser processing method of the present embodiment, because the long film F is continuously conveyed without being stopped when performing laser processing, the time required to convey the long film F is shortened. Further, no time is required to fix the long film F by suction or to release fixing by suction of the long film F. Therefore, it is possible to increase the productivity of laser processing of the long film F.

REFERENCE SIGNS LIST

[0074] 1 Optical Unit [0075] 2 Rotary Encoder [0076] 3 Control Device [0077] 11 Laser Beam Source [0078] 12 Optical Element [0079] 13 Galvanometer Scanner [0080] 100 Laser Processing Apparatus [0081] 131 Movable Lens [0082] 132 Condenser Lens [0083] 133 First Galvanometer Mirror [0084] 134 Second Galvanometer Mirror [0085] F Long Film [0086] L Laser Beam