Method for calculating the amount of air mixed in a film roll, method for controlling the amount of air mixed in, and device for calculating the amount of air mixed in

Abstract

To derive the amount of air mixed between films inside a film roll quantitatively with improved accuracy, and reduce a burden on incidental work necessary in applying to a manufacturing line of the film roll.SOLUTION: A method for deriving the amount of air mixed in a film roll includes: acquiring image information constituting a tomographic image of a plurality of layers of films laminated on a surface side of a film roll 50 through optical interference tomography using reflected light RL obtained from the plurality of layers of films; specifying a portion, in the acquired image information, which is formed based on the reflected light RL having an intensity below a preset threshold as noise; creating the tomographic image with the image information from which the specified noise is removed; measuring dimension information on a mixed air area formed between the adjacent films in the created tomographic image; and deriving the volume of the mixed air area by using the measured dimension information as a mixed air amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for determining the amount of air entrained in a film roll, a method for controlling the amount of air entrained using the method, and an apparatus for determining the amount of air entrained. [Background technology]

[0002] There is a known technology for manufacturing a film roll having multiple film layers formed thereon by winding up a flexible resin film or sheet (hereinafter simply referred to as "film").Regarding film rolls, for example, Patent Document 1 discloses a technology for inspecting the inside of a tape-shaped film by ultrasonic flaw detection and preventing the tape-shaped film from becoming unwound during transportation or storage.

[0003] Specifically, a tape-shaped film made of a resin such as PET (polyethylene terephthalate) wound around a core is submerged in a water tank. Electronic circuit components such as ICs are enclosed within the tape-shaped film. A correlation between the attenuation rate of ultrasonic waves corresponding to the depth from the surface of the tape-shaped film and the winding state is set in advance. In Patent Document 1, ultrasonic pulses are emitted onto the tape-shaped film using a water immersion flaw detection method, and the attenuation rate of the ultrasonic waves obtained from the tape-shaped film is compared with the set correlation to evaluate whether the winding state of the tape-shaped film is good.

[0004] Furthermore, Patent Document 2 discloses a technology for inspecting the surface of a resin film of a packaging roll body used for packaging food for wrinkles. In Patent Document 2, the surface of the outermost layer of the resin film of the packaging roll body is imaged using an illumination means and an imaging means such as a CCD camera, and the presence or absence of wrinkles is detected by analyzing the image.

[0005] Furthermore, although not a film roll, Patent Document 3 discloses a technique for inspecting resin members that uses optical coherence tomography (OCT). In Patent Document 3, a tomographic image of the interior of a resin member is created by performing predetermined signal processing on interference waves (interference fringes) obtained by light reflected from a resin member such as a PET bottle (reflected light) and light reflected from a reference mirror (reference light). The created tomographic image is then analyzed to inspect whether or not an intermediate resin layer of a type different from the surface resin layer exists inside the resin member. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5154186 [Patent Document 2] Patent Publication No. 2020-30118 [Patent Document 3] Patent Publication No. 2018-132324 Summary of the Invention [Problem to be solved by the invention]

[0007] Here, in the past, when various film rolls were manufactured, the film was often tightly wound to prevent wrinkles from forming on the surface of the wound film when it was wound up. It was believed that tightly winding the film prevented the formation of air-trapped regions between the layers of the wound film, which was advantageous for the transportation or storage of the film roll after winding.

[0008] However, the present inventors have found that, for example, in the case of a film roll in which electronic circuit components are disposed inside or on the surface of the film, it is preferable to intentionally wind the film loosely from the viewpoint of preventing damage to the electronic circuit components. In other words, it is preferable to wind the film loosely to a certain extent, without being too tight, while maintaining integrity, so that an air-entrained region having a desired volume (amount of air entrained) is formed between adjacent pieces of film inside the film roll while avoiding the occurrence of wrinkles.

[0009] Therefore, there is a need for a method for determining the amount of air trapped inside a film roll over time while the film is being wound, and for adjusting the winding state of the film in accordance with the determined amount of air trapped inside the film roll.

[0010] One specific method for deriving the amount of trapped air is for an operator to visually inspect the side of the film roll to confirm the shape of the air-trapped area and estimate the amount of trapped air based on the confirmed shape. However, when an operator inspects the film roll visually, the amount of trapped air is estimated based on human subjective experience. In other words, because the amount of trapped air is not measured quantitatively, there is a problem in that the objectivity and reproducibility of the inspection results are low.

[0011] Furthermore, the ultrasonic flaw detection technology in Patent Document 1 makes it possible to roughly estimate the quality of the internal condition of a film roll using the correlation between the attenuation rate and the winding state. However, because it is not possible to specifically analyze the internal structure between the films, it is difficult to quantitatively measure the amount of air trapped in the air-trapped regions formed between the films.

[0012] In addition, in the case of ultrasonic flaw detection, in order to efficiently transmit ultrasonic waves to the test piece, it is necessary to place a contact medium such as water or grease between the probe that emits the ultrasonic waves and the test piece. This requires work such as preparing a separate water tank to submerge the film roll, and as a result, the burden of additional work required when applying ultrasonic flaw detection to a film roll production line increases.

[0013] In addition, in the case of Patent Document 2, although it is possible to capture an image of the surface of the outermost layer of the film roll, it is not possible to capture an image of the structure between the films inside the film roll, and therefore it is not possible to derive the amount of air trapped in the air trapped area formed between the films inside.

[0014] Furthermore, while the OCT technology in Patent Document 3 is capable of analyzing tomographic images of the interior of a single layer of a resin component, it does not take into consideration analyzing the structure of the interior boundaries of a film roll in which air-trapped regions are formed between adjacent films. Specifically, in the case of a film roll in which relatively thin resin films are wound in a stacked state, when OCT measurement light is irradiated, multiple reflections, in which the light is repeatedly reflected two or more times, often occur on the surface of one or more layers of film inside the film roll.

[0015] For this reason, OCT tomographic images of film rolls in which films are wound in a stacked state contain image information acquired based on the reflected light from multiple reflections (hereinafter simply referred to as "multiple reflected light") that occur in each layer. Furthermore, the intensity of the reflected light obtained from the film material of film rolls for flexible substrates is often relatively high.

[0016] Therefore, when OCT is performed on a film roll, an image resembling the actual film structure may be formed in the tomographic image due to multiple reflections. In the following specification, a two-dimensional image portion in the tomographic image that resembles the actual film structure but differs from the portion corresponding to the actual film structure is referred to as a "ghost (virtual image)." Furthermore, among the image information serving as data constituting the two-dimensional tomographic image, the image information constituting the ghost is referred to as "noise."

[0017] Therefore, even if the OCT technology of Patent Document 3 is simply applied to a film roll, it is difficult to distinguish between ghost areas formed by noise in the tomographic image and areas that correspond to the actual film structure. As a result, it is difficult to clearly identify the air-trapped areas between films inside the film roll, making it difficult to accurately derive the amount of trapped air.

[0018] The present invention aims to provide a technology that can quantitatively and accurately derive the amount of air trapped between films inside a film roll, and that can reduce the burden of additional work required when applying the technology to a film roll manufacturing line. [Means for solving the problem]

[0019] The above problem can be solved by a method of deriving the amount of air mixed in a film roll according to one embodiment of the present invention, which involves acquiring image information constituting a tomographic image of the multiple layers of film by optical coherence tomography using reflected light obtained from multiple layers of film laminated on the surface side of the film roll, identifying as noise a portion of the acquired image information formed based on reflected light having an intensity below a predetermined threshold, creating a tomographic image using the image information from which the identified noise has been removed, measuring dimensional information of air-mixed regions formed between adjacent films in the created tomographic image, and using the measured dimensional information to derive the volume of the air-mixed region as the amount of air mixed in.

[0020] In one aspect of the present invention, by employing the above-described means, a tomographic image of multiple layers of film stacked in a film roll is created by optical coherence tomography. In the created tomographic image, air-mixed regions are formed between adjacent films. That is, the structure of the boundaries inside the film roll is visualized.

[0021] Then, dimensional information of the air-entrapped region in the tomographic image is measured, and the volume of the air-entrapped region is calculated as the amount of air trapped. Therefore, the calculation of the amount of air trapped does not depend on subjective empirical rules, as is the case with visual inspection by an operator. As a result, the amount of air trapped between films inside the film roll can be calculated quantitatively.

[0022] Furthermore, the amount of entrapped air can be calculated simply by using the tomographic images created by optical coherence tomography. In other words, unlike ultrasonic flaw detection, no contact medium is required, eliminating the need for additional work such as preparing a water tank. This reduces the burden of additional work required when applying the present invention to a film roll production line.

[0023] Furthermore, image information constituting a tomographic image is acquired, and a portion of the acquired image information formed based on reflected light having an intensity below a preset threshold is identified as noise. A tomographic image is then created using the image information from which the identified noise has been removed. This allows for more accurate distinction between film structure and noise in the tomographic image, thereby clearly identifying the air-inclusion region. As a result, the amount of air inclusion can be derived with increased accuracy.

[0024] In the above-described embodiment, the multi-layer film may include an outermost film of the film roll, and the threshold value may be set to a value equal to or greater than the maximum intensity of the multiple-reflected light in the outermost film.

[0025] Furthermore, in the above-described aspect, a circuit board may be formed on the film roll.

[0026] Furthermore, the above-mentioned problems can be solved by a method for controlling the amount of air mixed in a film roll according to another aspect of the present invention, in which, when the film is wound up while applying tension to the film to form a film roll, image information constituting a tomographic image of the multiple layers of film is obtained by optical coherence tomography using reflected light obtained from the multiple layers of film laminated on the surface side of the film roll, a tomographic image is created using the obtained image information, and the tension of the film is adjusted according to the state of the air mixed in area formed between adjacent films in the created tomographic image, thereby controlling the amount of air mixed in inside the film roll and forming a target amount of air mixed in area between adjacent films inside.

[0027] By taking the above-mentioned measures, in the above-mentioned another aspect, the tension T of the film is adjusted according to the state of the air-entrapped region formed between adjacent films in a tomographic image of the multi-layer film acquired by optical coherence tomography. This makes it easier to form an air-entrapped region having a target volume between adjacent films inside the film roll.

[0028] In the another aspect, the amount of mixed air as the state of the air-entrapped region may be derived using the method for deriving the amount of mixed air in a film roll according to the one aspect.

[0029] In another aspect described above, as the number of wound layers of the actual film roll increases with winding, the current position of the surface of the film roll that has moved from its initial position toward the scanning irradiation device of the measurement light can be detected in a tomographic image created from the image information, and at least one of the actual film roll and the scanning irradiation device can be moved according to the detected current position of the surface, thereby maintaining the distance between the surface of the actual film roll and the scanning irradiation device within a range where optical coherence tomography is possible.

[0030] Furthermore, the above problem can be solved by a device for deriving the amount of air mixed in a film roll according to yet another aspect of the present invention, which comprises a scanning irradiation device that irradiates the surface of the film roll while scanning it with measurement light, and a derivation unit that acquires image information constituting a tomographic image of the multiple layers of film by optical coherence tomography using reflected light obtained from the multiple layers of film stacked on the surface side of the film roll, identifies as noise a portion of the acquired image information formed based on reflected light having an intensity below a predetermined threshold, creates a tomographic image using the image information from which the identified noise has been removed, measures dimensional information of air mixed in regions formed between adjacent films in the created tomographic image, and derives the volume of the air mixed in region as the amount of air mixed in using the measured dimensional information.

[0031] By taking the above-mentioned measures, in the above-mentioned further aspect, as in the above-mentioned one aspect, the burden of ancillary work required during the production of film rolls can be reduced compared to the case of ultrasonic flaw detection methods, and therefore the air entrapment amount deriving device can be easily introduced into the film roll production line. [Effects of the Invention]

[0032] According to the present invention, the amount of air trapped between films inside a film roll can be calculated quantitatively and with high accuracy, and the burden of additional work required when applying the method to a film roll manufacturing line can be reduced. [Brief explanation of the drawings]

[0033] [Figure 1] 1A and 1B are diagrams illustrating the configuration of a device for deriving the amount of air mixed in a film roll according to an embodiment of the present invention. [Figure 2] 10 is a flowchart illustrating a method for deriving the amount of air mixed in the film roll according to the present embodiment. [Figure 3] FIG. 3(A) is a diagram illustrating a tomographic image (first comparative example) created using image information containing noise, and FIG. 3(B) is a diagram illustrating a tomographic image (first embodiment) created using image information from which noise has been removed. [Figure 4] FIG. 4(A) is a diagram illustrating a tomographic image (second comparative example) created using image information containing noise, and FIG. 4(B) is a diagram illustrating a tomographic image (second example) created using image information from which noise has been removed. [Figure 5] 10A to 10C are diagrams illustrating a method for controlling the amount of air mixed in the film roll according to the present embodiment. [Figure 6] FIG. 6(A) is a diagram illustrating a tomographic image created to detect the current position of the surface of the film roll, and FIG. 6(B) is a diagram illustrating a tomographic image in which all parts except the outermost surface of the tomographic image of FIG. 6(A) have been removed. DETAILED DESCRIPTION OF THE INVENTION

[0034] An embodiment of the present invention will be described below. In the following description of the drawings, identical or similar parts are designated by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each device or component, etc., differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, the drawings also include parts with different dimensional relationships and ratios.

[0035] 1, the device 10 for determining the amount of entrained air in a film roll according to this embodiment is provided in a production line 30 for forming a film roll by winding up a film while applying tension to the film. For ease of explanation, the device for determining the amount of entrained air in a film roll will hereinafter also be referred to simply as the "device for determining the amount of entrained air" or "determination device."

[0036] (Film roll production line) The lead-out device 10 is additionally installed on the film roll production line 30, for example, adjacent to a winding device used in the winding process located at the final stage of the production line 30. The winding device includes a winding core 32 to which one end of the film is fixed, a rotation drive device that applies torque F to the winding core 32 to rotate it, multiple transfer rolls that transfer the film toward the winding core 32 in the winding direction D, and a tension adjustment device 34. The rotation drive device is not shown, and the reference numerals of the transfer rolls are not added. Figure 1 illustrates the production line 30 in which the film is wound around the winding core 32 to form a film roll 50.

[0037] (Tension adjustment device) In this embodiment, the tension T applied to the film during winding is adjusted by the tension adjusting device 34. Specifically, a tension roll serving as the tension adjusting device 34 applies a desired amount of tension T to the film by pushing or pulling the film in the film thickness direction. The tension adjusting device 34 may also be included in the delivery device of the present invention. Furthermore, in the present invention, the method of adjusting the tension T is not limited to using a tension roll, and various known methods can be used, such as a method of applying tension by gripping the end of the film opposite the winding core 32.

[0038] Furthermore, the term "film roll" refers to a film in which multiple layers of film are laminated inside by winding up a single continuous, long film. The film is also optically transparent. In this embodiment, a winding core 32 is attached to one end of the long film, and the film roll 50 is shown as being wound up by the winding core 32, but the present invention is not limited to this.

[0039] For example, the film roll may be wound without using the winding core 32. Furthermore, the present invention is not limited to being applied to the film roll 50 being wound on the production line 30, but can also be applied to the film roll 50 in a completely wound state.

[0040] Furthermore, in this specification, when describing the surface of a film, the surface on the side of the winding core 32 (inside) where the film winding shaft is located is referred to as the "back side," and the surface on the side opposite the winding core 32 (outside) is referred to as the "front side." Furthermore, with regard to a film roll, unless otherwise specified, the "surface of the film roll" is exposed to the outside, and the "surface of the film roll" refers to the front surface of the outermost layer (first layer) of the film roll 50, including the film roll 50 in the process of being wound. In other words, with respect to the film roll 50 in the process of being wound, the position of the "surface of the film roll 50" moves from the side of the winding core 32 to the outside as the winding progresses over time.

[0041] The film roll 50 of this embodiment is a film made of a flexible resin such as PET. The film roll 50 of this embodiment is a film roll for producing a flexible substrate, with a circuit board formed on the surface of the film. However, the present invention is not limited to this, and for example, a circuit board may be formed inside the film. Also, the present invention does not necessarily require a circuit board to be formed on the film roll. Instead of a circuit board, for example, a coating layer made of a material other than resin may be provided on part or the entire surface of the film roll.

[0042] (Air entrainment amount derivation device) 1, the derivation device 10 includes a light source 12, a beam splitter 14, a scanning irradiation device 16, a moving stage 18, a reference mirror 20, a photodetector 22, a derivation unit 24, and a control unit 26. The derivation device 10 according to this embodiment exemplarily performs optical coherence tomography using reflected light RL obtained from a multi-layer film consisting of first to third layers stacked on the surface side of a film roll 50 by irradiation with measurement light DL. In other words, the derivation device 10 functions as an OCT device.

[0043] (OCT device) In an OCT device, by obtaining a resolution in the radial direction (depth direction) of the film roll, it is possible to create a tomographic image of the sample to be measured. The OCT device according to this embodiment is exemplified as a Mach-Zehnder interferometer in which the reflected light of light split by the beam splitter 14 reaches the photodetector 22 separately, but the present invention is not limited to this. A Michelson interferometer in which the reflected light of light split by the beam splitter 14 returns to the beam splitter 14 and then reaches the photodetector may also be used.

[0044] (light source, beam splitter) The light source 12 may be a broadband light source such as a superluminescent diode (SLD), an ultrashort pulsed laser, or a wavelength-swept light source. OCT measurement methods are broadly divided into two types: time-domain OCT and Fourier-domain OCT. While the light source and photodetector used differ, the present invention can be applied to any OCT. The light emitted from the light source 12 is split by a beam splitter 14 into measurement light DL and reference light CL1.

[0045] (Scanning irradiation device) In this embodiment, a probe serving as the scanning irradiation device 16 is provided in the OCT device. The scanning irradiation device 16 irradiates the film roll 50 with measurement light DL from the light source 12. The irradiation direction is toward the winding core 32. The scanning irradiation device 16 is provided with an angle adjustment mechanism (not shown) that changes the irradiation angle (tilt angle) of the measurement light DL with respect to the objective lens. Therefore, the scanning irradiation device 16 can irradiate the surface of the film roll 50 with the measurement light DL while scanning it along the radial direction of the objective lens. The radial direction of the objective lens, which is the scanning direction, overlaps with the circumferential direction of the film roll 50.

[0046] In this embodiment, the irradiation angle (measurement range) of the scanning irradiation device 16 is approximately 1 cm along the circumferential direction of the film roll 50. The irradiation angle depends on the specifications of the objective lens used to irradiate the measurement light DL. In this embodiment, OCT tomographic images can be created at a video rate of approximately 0.1 seconds, but in the present invention, the video rate value can be changed as appropriate.

[0047] The measurement light DL incident from the beam splitter 14 is reflected by a galvanometer mirror (not shown) provided in the scanning irradiation device 16 and is irradiated onto a film roll 50, which is a sample to be measured by OCT. After the irradiated measurement light DL is reflected or scattered by the film roll 50, the reflected light RL from the film roll 50 is guided to the photodetector 22 via the scanning irradiation device 16.

[0048] (reference mirror, photodetector) In this embodiment, the reference mirror 20 is, for example, a plane mirror that reflects the reference light CL1 incident thereon from the beam splitter 14. After the incident reference light CL1 is reflected by the reference mirror 20, the reference light CL2 from the reference mirror 20 is guided to the photodetector 22. The photodetector 22 detects the light intensity of the interference wave of the two guided light beams (reflected light RL, reference light CL2). The interference wave is measured by an imaging element such as a photodiode or line sensor (not shown).

[0049] (Derivation part) The derivation unit 24 performs predetermined signal processing on the measured interference wave. The derivation unit 24 can be configured as a computer equipped with, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), a storage device, an I / O port, etc. The CPU, RAM, storage device, and I / O port are not shown in the figures. The RAM, storage device, and I / O port are configured to be able to exchange data with the CPU via an internal bus.

[0050] The derivation unit 24 is configured to be connectable to an input / output device and an external storage device, both of which are not shown. The input / output device includes an output device such as a display. The storage device and the external storage device are configured, for example, by a flash memory, an HDD (Hard Disk Drive), etc.

[0051] Signal processing by the derivation unit 24 makes it possible to acquire image information (OCT signals) that constitute a depth-direction tomographic image at measurement points on the surface of the film roll 50. Any known processing method in OCT technology can be used as the signal processing method. Furthermore, the measurement points on the film roll 50 are scanned by driving the galvanometer mirror of the scanning irradiation device 16. By scanning, image information that constitutes a radial tomographic image at multiple measurement points on the scanning line is acquired. The derivation unit 24 uses the acquired image information to create a two-dimensional tomographic image of the interior of the film roll 50. The acquired image information, the created tomographic image, and the like can be displayed on an output device connected to the derivation unit 24.

[0052] In this embodiment, the measurement light DL is irradiated while being scanned along the circumferential direction of the film roll 50, and therefore the two-dimensional tomographic image that is created appears as a cross section perpendicular to the axis of the film roll 50. However, in the present invention, the irradiation direction of the measurement light DL is not limited to this, and other directions may be used. For example, by irradiating the film roll 50 with the measurement light while being scanned along the axial direction (width direction) of the film roll 50, the two-dimensional tomographic image that is created may appear as a cross section that includes the axis of the film roll 50 or a cross section that is parallel to the axis.

[0053] (Dimensions information) Furthermore, the derivation unit 24 can acquire, through image analysis processing, the distance, height, width, and cross-sectional area of ​​any portion in the tomographic image, for example, the structure of the front or back surface of the film, or the air-trapped region formed between adjacent films, as "dimensional information." The dimensional information is used in the method for deriving the amount of air trapped in a film roll according to this embodiment.

[0054] In this embodiment, "distance" in the tomographic image refers to the length measured along the circumferential direction of the film roll 50. Furthermore, "height" in the tomographic image refers to the length measured along the thickness direction of the film. Furthermore, "width" in the tomographic image refers to the length measured along the width direction of the film. Furthermore, "cross-sectional area" in the tomographic image refers to the area in the tomographic image that includes distance and height, or the area in the tomographic image that includes width and height.

[0055] (moving stage) The moving stage 18 is installed, for example, on the floor of the production line 30, and the scanning irradiation device 16 is placed above the moving stage 18. A linear motion mechanism, such as a feed screw or an air cylinder, is provided below the moving stage 18. The linear motion mechanism allows the moving stage 18 to freely move toward or away from the film roll 50 on the floor.

[0056] (Control unit) The control unit 26 can be configured as a computer including a CPU, RAM, a storage device, an I / O port, etc., similar to the derivation unit 24. In the present invention, the derivation unit and the control unit may be configured integrally.

[0057] The control unit 26 is connected to both the moving stage 18 and the tension adjustment device 34. The control unit 26 can adjust whether or not the moving stage 18, on which the scanning irradiation device 16 is placed, can move and the amount of movement. In other words, the relative position of the scanning irradiation device 16 and the film roll 50 is adjusted. The control unit 26 can also adjust the tension T that the tension adjustment device 34 applies to the film being wound up.

[0058] Next, a method for deriving the amount of air in a film roll and a method for controlling the amount of air used in the delivery device 10 according to this embodiment will be described in detail with reference to the flowchart in FIG. 2. The upper part of the flowchart in FIG. 2 illustrates a series of derivation processes (steps S1 to S6) related to the method for deriving the amount of air. The lower part of the flowchart illustrates a control process (steps S7 to S8) related to the method for controlling the amount of air, which is executed consecutively to the process for deriving the amount of air, and a relative position adjustment process (steps S9 to S10) related to the method for adjusting the relative position, which is executed in conjunction with the control process. Hereinafter, the process for deriving the amount of air will be simply referred to as the "deriving process." The process for controlling the amount of air will also be simply referred to as the "control process."

[0059] (Method of deriving the amount of air mixed in) 1, in a production line 30 for a film roll 50, a long film is wound at a constant peripheral speed while tension is applied to the film to form the film roll 50. In addition, a scanning irradiation device 16 is disposed at a constant initial distance G from the film roll 50.

[0060] Next, optical coherence tomography is performed on the multi-layer film laminated on the surface side of the film roll 50 as it is being wound, by scanning and irradiating the surface with measurement light DL using the extraction device 10 according to this embodiment (step S1 in FIG. 2). In this embodiment, the multi-layer film to be measured is the first to third layers. However, in the present invention, the multi-layer film to be measured is not limited to this, and may be, for example, a two-layer film consisting of only the first layer, which is the outermost layer of the film roll 50, and the second layer of film on the inside adjacent to the first layer of film.

[0061] Furthermore, although the measurement light DL of the OCT device is irradiated onto the surface of the outermost film layer of the film roll 50, it is not essential in the present invention that the outermost film layer of the film roll 50 be included in the multi-layer film to be measured. For example, the multi-layer film may be the second to fourth layers, or the third to sixth layers L6, etc. As long as a more accurate tomographic image can be created in OCT taking into account the reflectance of the film roll 50, any multi-layer film can be selected as the measurement target.

[0062] Next, the derivation unit 24 performs predetermined signal processing on the interference waves measured by optical coherence tomography, thereby acquiring image information constituting a tomographic image of the multi-layer film (step S2 in FIG. 2).

[0063] Next, the derivation unit 24 identifies, as noise, a portion of the acquired image information that is formed based on reflected light RL having an intensity lower than a preset threshold (step S3 in FIG. 2).

[0064] (threshold) Here, the types of reflected light RL returning to the OCT device from inside the film roll include reflected light that returns to the OCT device after being reflected once on the surface (front or back) of the film, and reflected light that returns to the OCT device after being reflected three or more times (multiple reflected light). Multiple reflected light can originate from any layer of film inside the film roll. Furthermore, among the returned multiple reflected light, the intensity of the multiple reflected light that returns after being reflected three times in the order of the back surface of the outermost layer (first layer), the front surface of the outermost layer film, and the back surface of the outermost layer film is the greatest.

[0065] In this embodiment, the lower limit, which is the smallest value in the setting range of the threshold intensity, is the intensity of the multiple-reflected light obtained after being reflected three times by the outermost film of the film roll 50. In other words, the maximum multiple-reflected light intensity among the multiple-reflected light intensities expected in the film roll 50 is set as the minimum value of the setting range of the threshold intensity.

[0066] The intensity of the reflected light RL that returns after being reflected once on the surface of the film and the maximum intensity of the multiple reflection light in the outermost film layer can be calculated using the reflectance of the film based on the film material. In the following, the term "multiple reflection light" refers to multiple reflection light that has an intensity below a preset threshold and generates noise in the OCT tomography of this embodiment, unless otherwise specified.

[0067] On the other hand, when the multi-layer film being measured is, for example, a film having first through third layers, the intensity of the reflected light RL reflected once from the front surface of the third layer is used as the upper threshold value. By setting the upper threshold value to the intensity of the reflected light RL from the front surface of the third layer, the innermost of the multi-layer film being measured, it becomes easier to confirm the boundary structure between the third layer of film and the adjacent second layer of film outside the third layer. In addition, in the present invention, when the outermost layers, the first through nth layers, of the film roll 50 are being measured, the intensity of the reflected light RL from the front surface of the nth layer can be set as the upper threshold value.

[0068] In this embodiment, the threshold is not set solely based on the intensity of the reflected light RL from the front surface of the nth layer, but is set with a certain range (margin) that is equal to or greater than the maximum intensity of the multiple reflection light in the outermost film. This prevents erroneous detection of noise and improves the accuracy of the tomographic image that is formed. Note that in the present invention, the threshold may be set separately using a value obtained by, for example, simulation, instead of the maximum intensity of the multiple reflection light in the outermost film.

[0069] Next, the derivation unit 24 removes the image information identified as noise from the image information acquired in step S2 (step S4 in FIG. 2). Then, a tomographic image of the multi-layer film is created using the image information from which the identified noise has been removed. Note that in the present invention, the noise removal method is not limited to this, and for example, a first tomographic image may be created using image information containing noise, and then a second tomographic image may be created by removing the noise from the image information acquired in step S2.

[0070] FIG. 3A illustrates a first tomographic image. The tomographic image in FIG. 3A shows two relatively bright bright lines representing the front surface L1A of the first layer and the back surface L1B of the first layer, respectively, and two relatively dark bright lines representing ghosts 60, one above and one below the two bright lines. The ghosts 60 are portions of the first tomographic image that are created by noise. FIG. 3B illustrates a second tomographic image as a first example of this embodiment. In the tomographic image in FIG. 3B, noise has been removed from the image information by the processing in step S4, and as a result, only the front surface L1A of the first layer and the back surface L1B of the first layer appear.

[0071] The first tomographic image in Figure 3(A) is a first comparative example for this embodiment. The upper ghost 60 in Figure 3(A) is not an image created by noise due to multiple reflections, but an image created based on noise inherent to the OCT device. On the other hand, the lower ghost 60 in Figure 3(A) is an image created by noise due to multiple reflections. The intensity of the multiple reflections is smaller than the maximum intensity of the multiple reflections in the outermost film in this embodiment.

[0072] Next, the derivation unit 24 measures dimensional information of the air-trapped region formed between adjacent films in the tomographic image created from the noise-removed image information (step S5 in FIG. 2). FIG. 4(A) illustrates a first tomographic image as a second comparative example obtained by scanning and irradiating the measurement light along the axial direction of the film roll 50, i.e., along the winding core 32.

[0073] 4(B) illustrates a second tomographic image in which the ghosts that appeared in FIG. 4(A) have been removed by removing noise, as a second example of this embodiment. In the second example, the threshold intensity range is set with the first layer L1 to the third layer L3 as the measurement target. FIG. 4(B) illustrates a tomographic image in which the multi-layer film to be measured is the first layer L1 to the third layer L3, and two air-containing regions 70, 72 are formed.

[0074] The "boundary structure" patterns of adjacent films stacked inside the film roll 50 are mainly the following two types (a) and (b). (a) The front and back surfaces of adjacent films are in close contact with each other without forming any air-trapped areas between them. (b) An air gap is formed between the front and back surfaces of adjacent films.

[0075] Specifically, the first tomographic image in Fig. 4(A) illustrates a state in which, from top to bottom, the outermost first layer L1, the second layer L2, the third layer L3, the fourth layer L4, the fifth layer L5, and the sixth layer L6 are stacked in this order. Directly below and to the right of the front surfaces L2A, L3A, and L4A of the second to fourth layers L2 to L4 in Fig. 4(A), ghosts 60 due to multiple reflections appear as multiple white lines extending in the left-right direction.

[0076] Furthermore, a ghost 60 due to multiple reflections appears as a white line extending in the left-right direction below the back surface L6B of the sixth layer L6 in the first tomographic image in Fig. 4(A). A white linear ghost 60 extending in the left-right direction also appears above the front surface L1A of the first layer L1 in the first tomographic image in Fig. 4(A). The ghost 60 on the upper side of the first layer L1 in Fig. 4(A) is an image created based on noise inherent to the OCT device.

[0077] Meanwhile, a first air-mixed region 70 is formed extending in the left-right direction at the boundary between the first layer L1 and the second layer L2 in the second tomographic image in Fig. 4(B). A second air-mixed region 72 is also formed extending in the left-right direction at the boundary between the third layer L3 and the fourth layer L4 in the second tomographic image in Fig. 4(B). The thickness of the second air-mixed region 72 measured in the up-down direction in Fig. 4(B) is thinner than that of the first air-mixed region 70.

[0078] In the second tomographic image, the back surface L2B of the second layer L2 and the front surface L3A of the third layer L3 are in close contact with each other, the back surface L4B of the fourth layer L4 and the front surface L5A of the fifth layer L5 are in close contact with each other, and the back surface L5B of the fifth layer L5 and the front surface L6A of the sixth layer L6 are in close contact with each other. No air-containing region is formed at the boundary between the layers in close contact with each other.

[0079] Next, the deriving unit 24 derives the volume of the air-entrapped region as the amount of entrapped air using the measured dimensional information (step S6 in FIG. 2). Specifically, for example, the amount of entrapped air can be derived by multiplying the measured "cross-sectional area" of the air-entrapped region by the "width of the film." The "width of the film" is the width of the film of the film roll 50 being wound. For example, "Cross-sectional area" = α, "film width" = β In this case, the amount of air mixed in can be calculated as "α×β".

[0080] (correction coefficient) In this embodiment, a correction coefficient may be used to supplement the dimensional information of any portion of the air-entrapped region that does not appear in the tomographic image. For example, the amount of air entrapped may be calculated as "α × β × γ" by multiplying the "cross-sectional area of ​​the air-entrapped region" × "film width" by a preset width correction coefficient γ. The correction coefficient can improve the accuracy of deriving the amount of air entrapped. This correction coefficient can be used in cases where the air-entrapped region is not formed across the entire width of the film but is formed partially, or in cases where the distance of the air-entrapped region is not constant but varies along the width.

[0081] In the present invention, the correction coefficient used to derive the amount of mixed air is not limited to the width, but can be set for each of the distance, height, width, and cross-sectional area of ​​the mixed air region in the tomographic image. In other words, the correction coefficient can be set when complementing the dimensional information of any part of the mixed air region that does not appear in the tomographic image.

[0082] For example, if the scanning direction of the measurement points on the film roll 50 is the axial direction of the film rather than the circumferential direction, the image of the air-inclusion region formed in the tomographic image has dimensions in the width direction and the height direction, but does not have a dimension in the distance direction. Therefore, when deriving the amount of air inclusion, the cross-sectional area can be multiplied by a preset distance correction coefficient as information to complement distance data that does not appear in the tomographic image.

[0083] As a specific method for designing the correction coefficients, for example, the correction coefficients can be set using values ​​obtained by simulations, experiments, etc., depending on the desired quality of the finished film roll 50. The simulations, experiments, etc. can be carried out by appropriately changing the film material, thickness, number of layers of the finished film roll 50, etc.

[0084] (Method for controlling the amount of air mixed in) Next, the derivation unit 24 determines whether the derived amount of mixed air satisfies a target amount that is set in consideration of the quality of the film roll 50 as a product (step S7 in FIG. 2). The target amount may be a single numerical value or may be set within a certain range. The target amount may also be set according to the amount of mixed air contained in a partial area displayed in one tomographic image of the formed film roll 50. The target amount may also be set according to the sum of the amounts of mixed air contained in multiple tomographic images, or may be weighted appropriately during the setting process.

[0085] If the result of the determination is that the derived amount of entrained air does not satisfy the target amount, the discharge unit 24 adjusts the actual tension of the film being wound on the production line 30 using the tension adjustment device 34 according to the derived amount of entrained air (step S8 in FIG. 2). The adjustment controls the amount of entrained air inside the film roll 50 being wound so that, after the adjustment, an air-entrained area of ​​the target amount is formed between adjacent films inside. For example, if the amount of entrained air is less than the target amount, the actual film tension is reduced, resulting in the film being wound relatively loosely. On the other hand, if the amount of entrained air is greater than the target amount, the actual film tension is increased, resulting in the film being wound relatively tightly.

[0086] 2, where the amount of air trapped inside the subsequent laminated film is calculated. That is, in this embodiment, feedback control is achieved by continuously calculating the amount of trapped air and adjusting the tension of the film according to the calculated amount of trapped air.

[0087] On the other hand, if the result of the determination in step S7 is that the derived amount of mixed air satisfies the target amount, the derivation unit 24 executes a relative position adjustment process. Note that even if the derived amount of mixed air does not satisfy the target amount in step S7, the relative position adjustment process from step S9 onwards may be executed in parallel with the process of deriving the amount of mixed air. The relative position adjustment process will be specifically described below.

[0088] (Relative position adjustment processing) In the production line 30, the number of layers wound up on the actual film roll 50 increases as the film roll 50 is wound. Therefore, as shown in Fig. 5, the position (current position) of the surface of the film roll 50 moves from the initial position at the start of the derivation method of this embodiment toward the scanning irradiation device 16 of the measurement light DL. In Fig. 5, the initial position of the surface of the film roll 50 is illustrated by a dashed-line box drawn inside the film roll 50.

[0089] In this embodiment, the derivation unit 24 detects the current position of the surface of the moved film roll 50 in a tomographic image created from image information from which noise has been removed (step S9 in FIG. 2). Specifically, image information other than that of the front surface of the first layer L1 is removed from the image information constituting the tomographic image by image processing. Then, the derivation unit 24 identifies position information of the front surface of the first layer L1 in the production line 30.

[0090] Fig. 6(A) shows an example of a tomographic image acquired when a first layer L1 to a sixth layer L6 of film are set as the multi-layer film to be measured. Fig. 6(B) shows an example of a tomographic image constructed from the remaining image information after image information other than the front surface L1A of the first layer L1, which includes noise, has been removed from the image information constituting the tomographic image of Fig. 6(A).

[0091] Next, the deriving unit 24 calculates the position of the surface of the film roll 50 being wound in the production line 30 as the current position using the position information of the identified front surface of the first layer L1. Then, the deriving unit 24 calculates the difference between the current position and the initial position. Next, the deriving unit 24 moves the moving stage 18 on which the scanning irradiation device 16 is mounted via the control unit 26 so that the scanning irradiation device 16 moves away from the film roll 50 by the calculated difference (step S10 in FIG. 2). Therefore, as shown in FIG. 5, the distance between the scanning irradiation device 16 and the current position of the surface of the film roll 50 is maintained at the same value as the initial distance G at the start of processing. Note that in the present invention, if the calculated difference is a value within a certain range, the movement via the control unit 26 may be suspended and not executed, and if the calculated difference is a value outside the certain range, the movement via the control unit 26 may be executed.

[0092] In the present embodiment, the relative position adjustment process is performed by moving the scanning irradiation device 16 backward relative to the film roll 50, but the present invention is not limited to this and may also be performed by moving the film roll 50 backward relative to the scanning irradiation device 16. Also, the initial gap G may be maintained by moving both the scanning irradiation device 16 and the film roll 50. In the present invention, as long as a state in which optical coherence tomography is possible is maintained, at least one of the actual film roll 50 and the scanning irradiation device 16 can be moved according to the detected current position of the surface of the film roll 50.

[0093] Furthermore, in the present embodiment, a case where a constant initial distance G is formed between the scanning irradiation device 16 and the film roll 50 has been exemplified, but in the present invention, the value of the initial distance can be changed arbitrarily as long as a distance that allows optical coherence tomography is formed. Furthermore, in the present invention, as long as optical coherence tomography is possible, a tomographic image can be created by OCT even when the scanning irradiation device 16 is in contact with the film roll 50. That is, in the present invention, a state in which the initial distance is zero and the scanning irradiation device 16 is in contact with the film roll 50 is not excluded.

[0094] 2, it is determined whether or not to end the winding of the film on the production line 30. If the winding is not to be ended, the processes from step S1 onward are repeated. On the other hand, if the winding is to be ended, the method for deriving the amount of entrained air in a film roll and the method for controlling the amount of entrained air according to this embodiment are ended.

[0095] In this embodiment, the processing of steps S1 to S11 includes at least a process of deriving the amount of mixed air (steps S1 to S6), a process of controlling the amount of mixed air (steps S1 to S8), and a process of adjusting the relative position (steps S1 to S4, S9 to S10). The process of deriving the amount of mixed air (steps S1 to S6) includes a process of forming a tomographic image (steps S1 to S4). In this embodiment, the series of processes of steps S1 to S11 have been described consecutively in FIG. 2, but the present invention is not limited to this.

[0096] In the present invention, the lead-out process (steps S1 to S6), the control process (steps S1 to S8), and the relative position adjustment process (steps S1 to S4, S9 to S10) may be performed individually and in parallel. By performing the lead-out process (steps S1 to S6), the control process (steps S1 to S8), and the relative position adjustment process (steps S1 to S4, S9 to S10) individually and in parallel, the production of the film roll 50 can be carried out more smoothly. Note that, for parallel execution, the number of lead-out devices 10 is not limited to one, and multiple units may be provided. Similarly, the number of each unit constituting the lead-out device 10, such as the lead-out unit 24, is not limited to one, and multiple units may be provided.

[0097] (Action and effect) In the method for deriving the amount of air trapped in a film roll according to this embodiment, optical coherence tomography is used to create a tomographic image of the multiple layers of film stacked in the film roll 50. In the created tomographic image, air trapped regions are formed between adjacent films. In other words, the structure of the boundaries inside the film roll is visualized.

[0098] Then, dimensional information of the air-entrapped region in the tomographic image is measured, and the volume of the air-entrapped region is calculated as the amount of air trapped. Therefore, the calculation of the amount of air trapped does not depend on subjective empirical rules, as is the case with visual inspection by an operator. As a result, the amount of air trapped between the films inside the film roll 50 can be calculated quantitatively.

[0099] Furthermore, the amount of entrapped air can be calculated simply by using the tomographic images created by optical coherence tomography. In other words, unlike ultrasonic flaw detection, no contact medium is required, and therefore no additional work, such as preparing a water tank, is required. This reduces the burden of additional work required when applying this embodiment to the production line 30 for the film roll 50.

[0100] Furthermore, image information constituting a tomographic image is acquired, and a portion of the acquired image information formed based on reflected light RL having an intensity below a preset threshold is identified as noise. A tomographic image is then created using the image information from which the identified noise has been removed. This allows for more accurate distinction between film structure and noise in the tomographic image, thereby clearly identifying air-inclusion regions. As a result, the amount of air inclusion can be derived with increased accuracy.

[0101] In this embodiment, the threshold value is set to a value equal to or greater than the maximum intensity of the multiple reflection light in the outermost film, so that all image information having a value less than the maximum intensity of the multiple reflection light is identified as noise, thereby enabling more efficient noise removal.

[0102] Furthermore, in this embodiment, damage to electronic circuit components mounted on the circuit board can be reduced, so that the film roll 50 for producing flexible boards and the like having flexibility can be manufactured with high quality.

[0103] Furthermore, in the method for controlling the amount of mixed air in a film roll according to the present embodiment, the tension T of the film is adjusted according to the amount of mixed air quantitatively and accurately derived by the drawing device 10. This makes it easy to form an air-mixed region with a target volume between adjacent films inside the film roll 50.

[0104] 5, as the film roll 50 is wound, the number of wound layers (thickness in the radial direction) actually increases, and the position of the surface of the film roll 50 moves from the initial position toward the scanning irradiation device 16 of the measurement light DL. If the film roll 50 comes into contact with the scanning irradiation device 16 during winding, and a force greater than the design range is applied to the film roll 50, damage such as scratches may occur on the film roll 50. The damaged film roll 50 has reduced commercial value.

[0105] For example, if a large force is applied to the scanning irradiation device 16 due to contact, the position of the scanning irradiation device 16 may be displaced, which may hinder the creation of accurate tomographic images and continuous imaging. There is also concern that the scanning irradiation device 16 may be damaged by contact.

[0106] However, in the method for controlling the amount of air mixed in a film roll according to this embodiment, a tomographic image created from image information from which noise has been removed is used to detect the current position of the surface of the moved film roll 50. Furthermore, at least one of the actual film roll 50 and the scanning irradiation device 16 is moved according to the detected current position of the surface, and the distance between the actual surface of the film roll 50 and the scanning irradiation device 16 is maintained within a range where optical coherence tomography is possible.

[0107] That is, the relative position between the actual surface of the film roll 50 and the scanning irradiation device 16 is adjusted in conjunction with the progress of winding. Therefore, even if the number of wound layers of the film roll 50 increases as the film roll 50 is wound, the surface of the film roll 50 is prevented from coming into contact with the scanning irradiation device 16, and as a result, the amount of mixed air can be stably and continuously derived.

[0108] Furthermore, compared to the ultrasonic flaw detection method, the device 10 for deriving the amount of trapped air in a film roll according to this embodiment can reduce the burden of incidental work required during the production of the film roll 50. Therefore, the device 10 for deriving the amount of trapped air in a film roll 50 can be easily introduced into the production line 30 for the film roll 50.

[0109] <Other embodiments> Although the present invention has been described using the above disclosed embodiments, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. For example, in the relative position adjustment process (steps S1 to S4, S9 to S10) of this embodiment, the current position of the surface of the film roll 50 is detected using the tomographic image formed in the tomographic image formation process (steps S1 to S4), but the present invention is not limited to this.

[0110] In the relative position adjustment process of the present invention, the current position of the surface of the film roll 50 may be detected by an imaging device such as a camera installed on the production line 30. Then, the film roll or the scanning irradiation device may be moved based on the detected current position, thereby adjusting the relative position between the film roll and the scanning irradiation device.

[0111] In this embodiment, a portion of the acquired image information formed based on reflected light having an intensity below a preset threshold is identified as noise, and a tomographic image is created using the image information from which the identified noise has been removed. As shown in Fig. 4(B), an air-trapped region formed between adjacent films is identified in the created tomographic image, and dimensional information of the identified air-trapped region is measured. However, in the present invention, the method for identifying the air-trapped region is not limited to this, and other methods can also be used as appropriate.

[0112] For example, in the present invention, the air-mixed region may be identified using image information that identifies the structure of the film surface without removing noise. In this embodiment, the first tomographic image in FIG. 4A contains ghosts due to noise. Furthermore, a second tomographic image with noise removed was created based on the first tomographic image, as shown in FIG. 4B.

[0113] However, by extracting only reflected light with a certain intensity from the tomographic image of Figure 4(A), it is possible to identify the structural portions of the film surface. Furthermore, the distance between the white bright lines corresponding to the identified structural portions of the film surface is measured in the tomographic image. If the measured distance differs from the actual film thickness by a predetermined value or more, the region having a difference of the predetermined value or more can be identified as an "air-containing region." In other words, in the present invention, it is possible to identify air-containing regions in the tomographic image by measuring the distance between the structural portions of the film surface without necessarily removing noise.

[0114] Furthermore, in the present embodiment, the method for controlling the amount of entrained air has been described by way of example, with respect to a case where the amount of entrained air is controlled using a method for deriving the amount of entrained air and a case where the relative position is adjusted. However, the present invention does not require the use of a method for deriving the amount of entrained air. For example, in the present invention, after measuring the entrained air region inside the film roll using an OCT device to form a tomographic image, an operator may estimate the amount of entrained air by visually observing the state of the entrained air region in the tomographic image without deriving the amount of entrained air. The state of the entrained air region may be, for example, the distance, height (thickness), width, cross-sectional area, etc., of the entrained air region, which have been described as "dimensional information."

[0115] Then, the tension of the film may be appropriately adjusted based on the operator's estimate. Furthermore, based on the operator's estimate, at least one of the actual film roll and the scanning irradiation device may be moved to maintain a state in which optical coherence tomography is possible. That is, the specific amount of air mixed in is an example of the state of the air mixed in region in the present invention, and the state of the air mixed in region is not limited thereto. In the present invention, even without specifically measuring the amount of air mixed in, the amount of air mixed in the film roll can be controlled according to the state of the air mixed in region in the tomographic image, and the relative position of the film roll and the scanning irradiation device can be adjusted.

[0116] As described above, the present invention includes various embodiments not described above, and the technical scope of the present invention is defined only by the invention-specifying matters in the claims that are appropriate from the above explanation. [Explanation of symbols]

[0117] 10 Derivation device 12 light source 14 Beam Splitter 16 Scanning irradiation device 18 Moving Stage 20 Reference mirror 22 Photodetector 24 Derivation part 26 Control Unit 30 production lines 32 Winding core 34 Tension adjustment device 50 film rolls 60 Ghost (Illusion) 70,72 Air entrapment area CL1, CL2 reference light D Winding direction DL measurement light F Torque G Initial Interval L1 1st layer L1A front L1B back side L2 2nd layer L3 layer L4 layer L5 floor L6 floor RL reflected light T tension

Claims

1. Light is irradiated from the surface of the film roll toward the core of the film roll, Obtaining image information constituting a tomographic image of the multiple layers of film by optical coherence tomography using reflected light obtained from the multiple layers of film loaded on the surface side of the film roll; Identifying as noise, among the acquired image information, a portion formed based on reflected light having an intensity lower than the intensity of the multiple reflection light from the first film layer, which is the outermost layer, or the intensity of the multiple reflection light from the nth film layer to be measured, or identifying as noise a portion formed based on reflected light having an intensity lower than the intensity of the reflected light from the front surface of the nth layer of the film roll; A tomographic image is created using the image information from which the identified noise has been removed, Dimensional information of an air-mixed region determined to have formed between adjacent films in the created tomographic image is measured; Using the measured dimensional information, the volume of the air entrapped region is calculated as the amount of entrapped air. A method for calculating the amount of air trapped in a film roll.

2. A method for deriving the amount of air entrapped in a film roll as described in claim 1, which measures dimensional information of an air entrapment area determined to have formed between at least one pair of adjacent films designated as measurement targets in the created tomographic image.

3. A circuit board is formed on the film roll. The method for deriving the amount of air entrained in a film roll according to claim 1 or 2.

Images