Sheet material production device and sheet material production method

Abstract

The present disclosure provides a sheet production device and a sheet production method, wherein the sheet production device (1) applies a coating material to a sheet material (11) to produce a multilayer sheet. The sheet production device (1) includes: a radiation light source that emits radiation light; a splitter that splits the radiation light into a measurement light that is incident on the multilayer sheet and a reference light that is irradiated on a reference surface; and an optical component that emits the measurement light toward the multilayer sheet and incidents the measurement light reflected by the multilayer sheet. The sheet production device (1) also includes: an interference detection unit that detects interference light between the measurement light reflected by the multilayer sheet and the reference light reflected by the reference surface; and a thickness calculation unit (62) that calculates the thickness of the sheet material (11) and the coating material of the multilayer sheet based on the detected interference light. As a result, the cycle time from the production of the multilayer sheet to the calculation of the thickness can be shortened.

Description

Technical Field

[0001] The present disclosure relates to a sheet material production device and a sheet material production method. Background Art

[0002] In a strip-shaped laminated sheet including a plurality of layers, the thickness inspection of the laminated sheet is important in view of its characteristics. As an apparatus for inspecting the thickness of the laminated sheet, for example, Japanese Patent Application Laid-Open No. 5-185022 (hereinafter referred to as "Patent Document 1") discloses a device for inspecting the thickness of the laminated sheet. Figure 10 The device shown.

[0003] The device for inspecting the thickness of a laminated sheet described in Patent Document 1 includes a scraper 92 positioned closer to the metal plate 91 to be conveyed than the resin 90 coating position, and controls the thickness of the applied resin 90. Furthermore, the device includes an X-ray thickness gauge 93 positioned closer to the metal plate 91 to be conveyed than the resin 90 coating position. The device of Patent Document 1 first measures the thickness of the metal plate 91 using the X-ray thickness gauge 93. Then, a calculation unit 94 advances and retracts the scraper 92 relative to the metal plate 91 based on the deviation in the measured thickness of the metal plate 91. This reduces unevenness in the film thickness of the resin 90 applied to the metal plate 91.

[0004] However, in the technology of Patent Document 1, the thickness of the laminated sheet after the resin 90 is coated is not checked. Therefore, there is a concern that a laminated sheet of the desired thickness cannot be manufactured. Therefore, it is conceivable to also set an X-ray thickness gauge 93 at a position closer to the conveying target side of the metal plate 91 than the resin 90 coating position, and use the X-ray thickness gauge 93 to check the thickness of the laminated sheet. However, in such a structure, the laminated sheet needs to be clamped from the front and back sides by the X-ray irradiation part and detection part of the X-ray thickness gauge 93. Furthermore, the above-mentioned device requires a cover body for explosion-proofing, etc. Therefore, the installation location of the X-ray thickness gauge 93 is limited. That is, the resin coating position and the inspection position are physically far apart. As a result, there is a concern that the cycle time from the resin coating to the acquisition of the thickness of the laminated sheet will become longer. Summary of the Invention

[0005] The present disclosure provides a sheet production apparatus and a sheet production method capable of shortening the tact time from the start of production of a multilayer sheet to the completion of thickness calculation.

[0006] The sheet production device disclosed herein is a sheet production device that produces a multilayer sheet by applying a coating material to a conveyed sheet material. The sheet production device includes: a radiation light source that emits radiation light; a splitter that splits the radiation light into measurement light that is incident on the multilayer sheet material and reference light that is irradiated on a reference surface; and an optical component that emits the measurement light toward the multilayer sheet material and also receives the measurement light reflected by the multilayer sheet material. Furthermore, the sheet production device includes: an interference detection unit that detects interference light resulting from interference between the measurement light reflected by the multilayer sheet material and the reference light reflected by the reference surface; and a thickness calculation unit that calculates the thickness of the sheet material and the coating material of the multilayer sheet material based on the detected interference light.

[0007] The sheet manufacturing method disclosed herein is a method for manufacturing a multilayer sheet by applying a coating material to a conveyed sheet material. The sheet manufacturing method includes: emitting radiation light from a radiation light source; dividing the radiation light into measurement light and reference light; and emitting the measurement light toward the multilayer sheet via an optical component, and causing the measurement light reflected by the multilayer sheet to enter the optical component. Furthermore, the sheet manufacturing method includes: irradiating the reference light onto a reference surface; detecting interference light resulting from interference between the measurement light reflected by the multilayer sheet and the reference light reflected by the reference surface; and calculating the thickness of the sheet material and the coating material of the multilayer sheet based on the detected interference light.

[0008] According to the present disclosure, it is possible to provide a sheet production apparatus and a sheet production method capable of shortening the tact time from the start of production of a multilayer sheet to the completion of calculation of the thickness of the multilayer sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram showing a schematic configuration of a sheet production device in Embodiment 1 of the present disclosure.

[0010] Figure 2 Schematic diagram showing the configuration of the SS-OCT apparatus in Embodiment 1 and Embodiment 2 of the present disclosure.

[0011] Figure 3 This is a flowchart showing the sheet production method in the first embodiment.

[0012] Figure 4A It is a YZ plan view showing the positional relationship between the objective lens and the multilayer sheet of the SS-OCT apparatus in Embodiment 1 and Embodiment 2.

[0013] Figure 4B It is an XY plan view showing the positional relationship between the inspection roller and the multilayer sheet of the SS-OCT apparatus in the first and second embodiments.

[0014] Figure 5AThis is a schematic diagram showing the positional relationship between the measurement light and the multilayer sheet when B scans are performed at different B scan positions on the inspection roller and the same B scan position on the multilayer sheet in Embodiments 1 and 2.

[0015] Figure 5B This is a schematic diagram showing the positional relationship between the measurement light and the multilayer sheet when the B scan is performed at different B scan positions on the inspection roller and also on the multilayer sheet in the first and second embodiments.

[0016] Figure 5C This is a schematic diagram showing the positional relationship between the measuring light and the multilayer sheet when the B scan is performed at the same B scan position on the inspection roller and at different B scan positions on the multilayer sheet in the state where the conveying speed of the multilayer sheet is reduced in embodiments 1 and 2.

[0017] Figure 6A It is a cross-sectional view taken along the YZ plane showing the periodic structure of the sheet material in the multilayer sheet in the first and second embodiments.

[0018] Figure 6B It is an XY plan view showing the positional relationship between the inspection roller and the multilayer sheet of the SS-OCT apparatus in the first and second embodiments.

[0019] Figure 6C It is an XY plan view showing the periodic structure of the sheet material in the multilayer sheet in the first and second embodiments.

[0020] Figure 7A Schematic diagram showing the refraction state of measurement light in the multilayer sheet in Embodiment 1 and Embodiment 2.

[0021] Figure 7B It is an explanatory diagram of the calculation method of the thickness of the multilayer sheet in the first embodiment and the second embodiment.

[0022] Figure 8 This is a schematic diagram showing a schematic configuration of a sheet production apparatus in a second embodiment.

[0023] Figure 9 This is a flowchart showing the sheet production method in the second embodiment.

[0024] Figure 10 This is an explanatory diagram of the prior art described in Patent Document 1. DETAILED DESCRIPTION

[0025] Refer to the attached Figure 1 Each embodiment of the present disclosure will be described.

[0026] (Implementation Method 1)

[0027] Hereinafter, the sheet material production apparatus in the first embodiment of the present disclosure will be described item by item.

[0028] <Schematic Structure of Sheet Production Apparatus>

[0029] First, use Figure 1 A schematic configuration of the sheet production apparatus 1 in Embodiment 1 of the present disclosure will be described.

[0030] Figure 1 Schematic diagram of the sheet material production device 1 in the embodiment 1 of the present disclosure. Figure 1 The directions are described with reference to the X, Y, and Z axes shown. Specifically, the Y axis corresponds to the length direction or conveying direction of the sheet material 11 or the multilayer sheet 10. Furthermore, the X axis corresponds to the direction orthogonal to the width direction or conveying direction of the sheet material 11 or the multilayer sheet 10.

[0031] The sheet material production device 1 is a device for producing a sheet material 11 coated with a coating material 12 (refer to Figure 6A ) of a multilayer sheet 10 and an apparatus for inspecting the multilayer sheet 10.

[0032] Specifically, if Figure 1 As shown, the sheet production apparatus 1 of the first embodiment includes a sheet supply reel 20, a coating unit 30, a winding roller 40, an SS-OCT device 50, and a sheet production control unit 60. The SS-OCT is an abbreviation for Swept-Source Optical Coherence Tomography.

[0033] The rotation axis of the sheet supply reel 20 is arranged parallel to the X-axis. A sheet material 11 wound in a roll is mounted on the sheet supply reel 20. The sheet supply reel 20 supplies the sheet material 11 to the coating unit 30. The sheet material 11 serves as the base material of the multilayer sheet 10 and may be, for example, a sheet made of a resin such as cellophane resin or polyimide resin, or a cloth or nonwoven fabric woven from cotton, resin fiber, or glass fiber.

[0034] Furthermore, the coating unit 30 includes a coating roller 31 , a coating supplier 32 , a coater 33 , and the like.

[0035] The coating roller 31 is provided on the conveying direction side (−Y direction side) of the sheet material 11 with respect to the sheet supply reel 20 , and its rotation axis is parallel to the X axis.

[0036] The coating supply device 32 supplies the coating material 12 to the coater 33. The coating material 12 is, for example, an adhesive made of a resin such as epoxy or acrylic, or a filler applied to reinforce the mechanical strength of the fiber or improve its weather resistance.

[0037] The applicator 33 is positioned above the coating roller 31 (on the -Z side). The applicator 33 applies the coating material 12 supplied from the coating supply 32 to the sheet material 11 conveyed on the coating roller 31. This laminates the coating material 12 onto the sheet material 11, forming a multilayer sheet 10. The multilayer sheet 10 is an example of an object to be measured. Specifically, the multilayer sheet 10 is, for example, an adhesive tape.

[0038] The method of applying the coating material 12 to the sheet material 11 is not limited to the method using the applicator 33. For example, the coating material 12 may be applied to the sheet material 11 by passing the sheet material 11 through a tank filled with the coating material 12. Alternatively, the coating material 12 may be applied to the sheet material 11 by bringing another roller coated with the coating material 12 into contact with the sheet material 11. Furthermore, the coating material 12 may be applied to both sides of the sheet material 11.

[0039] In addition, the multilayer sheet 10 described above is described as comprising a two-layer structure of a substrate and a resin layer, but the invention is not limited thereto. For example, the multilayer sheet 10 may be constructed as a multilayer structure comprising multiple coating layers and multiple substrates. Furthermore, when forming the multilayer sheet 10, after the coating material 12 is applied to the sheet material 11 described later, a drying step using a heater, hot air, or the like may be provided.

[0040] The winding roller 40 of the sheet production device 1 is positioned closer to the supply direction (-Y direction) of the sheet material 11 than the applicator 33, with its rotation axis parallel to the X-axis. The winding roller 40 is driven by a motor or the like to rotate, thereby winding the multilayer sheet 10. While the above description uses the example of a step of winding the multilayer sheet 10 by the winding roller 40, the present invention is not limited to this. For example, a cutting step of cutting the multilayer sheet 10 into sheets of a predetermined length may be provided instead of a winding step. Furthermore, a configuration may be adopted in which the multilayer sheet 10 is continuously connected in a subsequent step, rather than a winding step.

[0041] Furthermore, the SS-OCT device 50 of the sheet production apparatus 1 outputs various information used for calculating the thicknesses of the sheet material 11 and the coating material 12 constituting the multilayer sheet 10 to the sheet production control unit 60. The detailed structure of the SS-OCT device 50 will be described later.

[0042] The sheet production control unit 60 includes an operation control unit 61 , a thickness calculation unit 62 , a determination unit 63 , a storage unit 64 , a display unit 65 , and the like, and controls the overall operation of the sheet production apparatus 1 .

[0043] The operation control unit 61 controls the production operation of the multilayer sheet 10 .

[0044] The thickness calculation unit 62 calculates the thicknesses of the sheet material 11 and the coating material 12 based on the information from the SS-OCT apparatus 50 .

[0045] The determination unit 63 determines whether the multilayer sheet 10 is acceptable (OK or NG) based on the calculation result of the thickness calculated by the thickness calculation unit 62 .

[0046] The storage unit 64 stores the fact that the multilayer sheet 10 is an NG product in association with the manufacturing number and the like marked on the multilayer sheet 10 .

[0047] The display unit 65 displays whether the multilayer sheet 10 is an OK product or an NG product based on the determination result of the determination unit 63 .

[0048] <About SS-OCT devices>

[0049] Next, refer to Figure 2 Next, the structure of the SS-OCT apparatus 50 will be described. Figure 2 is a schematic diagram showing the structure of an SS-OCT apparatus.

[0050] The SS-OCT device 50 is an example of an inspection device and is an optical interference signal measuring device using wavelength-sweep optical coherence tomography (SS-OCT).

[0051] Optical Coherence Tomography (OCT) is a measurement method that utilizes the interference phenomenon of light. Specifically, OCT splits light emitted from a light source into reference light and measurement light L. The reference light is incident on a reference surface, while the measurement light L is incident on the object being measured. An interference signal is then detected by causing the reference light reflected by the reference surface to interfere with the measurement light L reflected by the object being measured. OCT then detects the position of the object being measured based on this detected interference signal.

[0052] There are two broad types of OCT: time-domain OCT (TD-OCT), which requires scanning of a reference plane, and frequency-domain OCT (FD-OCT), which does not. FD-OCT also includes spectrometer-based and wavelength-sweep-based methods. Wavelength-sweep-based FD-OCT is known as SS-OCT, as mentioned above. SS-OCT detects interfering light by temporally varying the frequency of light emitted from a light source.

[0053] The SS-OCT device 50 includes an inspection roller 51 , a measuring head 52 , a fiber interferometer 53 , and the like.

[0054] The inspection roller 51 is disposed between the coating roller 31 and the winding roller 40 , with its rotation axis parallel to the X axis. The inspection roller 51 is disposed to contact the multilayer sheet 10 at an angle α. Thus, the surface of the inspection roller 51 in contact with the multilayer sheet 10 forms an arc surface 511 .

[0055] The measuring head 52 functions as an example of an optical component and includes an illumination collimating lens 521, a galvanometer mirror pair 522, an objective lens 523, and a drive unit 524. The term "galvanometer mirror pair" refers to a pair of galvanometer mirrors, and the same applies to the following description.

[0056] The irradiation collimator lens 521 is connected to a second circulator 536 of the fiber interferometer 53 described later. The irradiation collimator lens 521 converts the measurement light L incident from the second circulator 536 into parallel light. The parallel light is emitted toward the galvanometer mirror pair 522.

[0057] The galvanometer mirror pair 522 is disposed above the inspection roller 51. The galvanometer mirror pair 522 includes a first mirror having a rotation axis parallel to the X-axis and a second mirror having a rotation axis parallel to the Y-axis. The galvanometer mirror pair 522 reflects parallel light incident from the illumination collimator lens 521 and directs the light toward the objective lens 523.

[0058] The objective lens 523 is disposed between the galvanometer mirror pair 522 and the inspection roller 51. The objective lens 523 focuses parallel light incident from the galvanometer mirror pair 522 and illuminates the multilayer sheet 10. The objective lens 523 is configured to form a telecentric optical system in combination with the galvanometer mirror pair 522. Thus, while the incident position of the measurement light L changes within the XY plane (horizontal plane) due to the movement of the first and second mirrors of the galvanometer mirror pair 522, the angle of incidence of the measurement light L does not change.

[0059] The driving unit 524 moves the first mirror and the second mirror of the galvanometer mirror pair 522 to adjust the incident position of the measurement light L with respect to the multilayer sheet 10 .

[0060] With the above-described structure of the measuring head 52, the measuring light L is incident from the second circulator 536 onto the irradiation collimator lens 521. As described above, the incident measuring light L passes through the galvanometer mirror pair 522, is focused by the objective lens 523, and is incident on the surface of the multilayer sheet 10. The measuring light L incident on the surface of the multilayer sheet 10 is reflected (or backscattered) by the surface, interior, and backside of the multilayer sheet 10 and the inspection roller 51. The reflected measuring light L then passes through the objective lens 523, the galvanometer mirror pair 522, and the irradiation collimator lens 521, and is emitted toward the second circulator 536.

[0061] The fiber interferometer 53 functions as an example of a light source unit and includes a radiation source 531, a first coupler 532, a first circulator 533, a reference collimating lens 534, a reference surface 535, a second circulator 536, a second coupler 537, a differential amplifier 538, and an OCT processing unit 539.

[0062] The radiation light source 531 emits radiation light. The radiation light source 531 is configured to be able to change the wavelength of the radiation light. The light emission port of the radiation light source 531 is connected to the light receiving port of the first coupler 532 .

[0063] The first coupler 532 functions as an example of a splitter that splits the light incident from the radiation source 531 into two, for example, at a fixed ratio of 50:50. The first coupler 532 has a first light output port and a second light output port (not shown). The first light output port is connected to the first circulator 533. The second light output port is connected to the second circulator 536. With this configuration, the radiation light incident from the radiation source 531 into the first coupler 532 is split into reference light and measurement light L. The reference light is emitted toward the first circulator 533, and the measurement light L is emitted toward the second circulator 536.

[0064] The first circulator 533 is connected to the light receiving port of the second coupler 537. The first circulator 533 emits the reference light incident from the first coupler 532 to the reference collimating lens 534. The reference light incident on the reference collimating lens 534 is reflected by the reference surface 535 and emitted toward the first circulator 533 via the reference collimating lens 534. The first circulator 533 emits the reference light reflected from the reference surface 535 to the second coupler 537.

[0065] The second circulator 536 is connected to the light receiving port of the second coupler 537 and the light receiving port of the irradiation collimating lens 521 of the measuring head 52. Thus, the second circulator 536 emits the measurement light L incident from the first coupler 532 to the measuring head 52, and emits the measurement light L from the measuring head 52 to the second coupler 537.

[0066] The second coupler 537 is connected to the differential amplifier 538. The second coupler 537 forms interference light based on the reference light from the first circulator 533 and the measurement light L from the second circulator 536. In other words, the second coupler 537 functions as an example of a multiplexing unit for the reference light and the measurement light L.

[0067] The differential amplifier 538 differentially transmits the beat signal of the interfering light generated by the second coupler 537 to the OCT processing unit 539. At this time, the frequency of the radiation light emitted from the radiation source 531 changes over time. Consequently, a frequency difference corresponding to the time delay is generated between the interfering reference light and the measurement light L in the second coupler 537. This frequency difference becomes the beat signal of the interfering light.

[0068] The OCT processing unit 539 includes an analog / digital conversion circuit 539A (analog / digital conversion unit), a Fourier transform circuit (Fourier transform unit) 539B, and a computing unit 539C. The Fourier transform circuit 539B functions as an interference detection unit, and the computing unit 539C functions as a distribution acquisition unit.

[0069] The analog / digital conversion circuit 539A is connected to the differential amplifier 538. The analog / digital conversion circuit 539A converts the temporal waveform of the optical beat signal of the interference light formed by the differential amplifier 538 from analog to digital.

[0070] The Fourier transform circuit 539B is connected to the analog / digital conversion circuit 539A. The Fourier transform circuit 539B detects the beat signal of the interfering light from the analog / digital conversion circuit 539A. The Fourier transform circuit 539B performs a Fourier transform on the detected beat signal and performs frequency analysis. This generates an SS-OCT signal representing the intensity distribution of the interfering light.

[0071] The input section of the calculation unit 539C is connected to the Fourier transform circuit 539B. Based on the information (SS-OCT signal) input from the Fourier transform circuit 539B, the calculation unit 539C calculates the reflected signal intensity distribution, which is the intensity distribution (profile) of the interference light at the incident position of the measurement light L. The process of obtaining the one-dimensional reflected signal intensity distribution in the incident direction at a single point where the measurement light L is incident will be described as "A scan."

[0072] The output unit of the calculation unit 539C is connected to the radiation source 531, the drive unit 524 of the galvanometer mirror pair 522 of the measuring head 52, and the sheet production control unit 60 (see Figure 1 ) is connected. The computing unit 539C controls the driver 524 to operate the galvanometer mirror pair 522. Specifically, the computing unit 539C performs the aforementioned A-scan while varying the incident position of the measurement light L. This allows the computing unit 539C to obtain the reflected signal intensity distribution at the linearly varying incident positions of the measurement light L and to generate a two-dimensional image of the distribution. The process of obtaining the reflected signal intensity distribution at multiple two-dimensionally imaged incident positions of the measurement light L will be described below as a "B-scan," and the resulting two-dimensional image as a "B-scan image."

[0073] and, Figure 1 The sheet generation control unit 60 shown performs predetermined operations such as calculation of the thickness of the multilayer sheet 10 based on information obtained by the A scan or the B scan under the control of the calculation unit 539C.

[0074] In the first embodiment and the second embodiment described below, the aforementioned TD-OCT can also be used. However, when using TD-OCT, for example, SS-OCT or SD-OCT, which can be performed at a frequency of 10 kHz or higher, is preferably used as the one-dimensional scan referred to as the A-scan. This can increase the speed of measuring the thickness of the multilayer sheet 10.

[0075] <About the installation position and scanning direction of the measuring head>

[0076] Next, refer to Figure 2 The installation position and scanning direction of the measuring head 52 will be described.

[0077] As described above, the multilayer sheet 10 and the outer peripheral surface of the inspection roller 51 maintain contact at an angle α. The measuring head 52 is configured so that, within the operating range of the galvanometer mirror pair 522, the measuring light L is incident perpendicularly on the arcuate surface 511 where the multilayer sheet 10 and the inspection roller 51 meet. This configuration suppresses refraction of the measuring light L between air and the multilayer sheet 10. Consequently, the thickness of the multilayer sheet 10 can be measured more accurately.

[0078] The rotation axis of the second mirror of the galvanometer mirror pair 522 is arranged parallel to the Y axis. This configuration allows the B scan to be performed by moving the incident position of the measurement light L in the axial direction of the inspection roller 51 , that is, in the X axis direction.

[0079] <Sheet production method>

[0080] Next, refer to Figure 1 as well as Figure 2 While using Figure 3 A sheet production method performed by the sheet production apparatus 1 will be described. Figure 3 is a flowchart showing a sheet production method.

[0081] First, if Figure 3 As shown, the coil will be wound on Figure 1 The wound end of the sheet material 11 on the sheet supply reel 20 shown is extended and placed on the winding roller 40 (step S1). Step S1 can be performed by an operator or automatically by providing a gripping unit for gripping the sheet material 11. Examples of methods for placing the sheet material 11 on the winding roller 40 include providing an openable slit in the winding roller 40 and holding the sheet material 11 in the slit.

[0082] Next, a multilayer sheet 10 is produced (step S2). Specifically, the motion control unit 61 of the sheet production control unit 60 rotates the winding roller 40 in a counterclockwise direction. At this time, the motion control unit 61 feeds the coating material 12 from the coating feeder 32 to the coater 33 while conveying the sheet material 11. Alternatively, as a method for feeding the coating material 12, for example, compressed air or a pump such as a diaphragm pump can be used. Thus, the coating material 12 is applied to the surface of the sheet material 11, producing the multilayer sheet 10. The produced multilayer sheet 10 is continuously wound around the winding roller 40.

[0083] Next, the SS-OCT apparatus 50 performs SS-OCT measurement on the multilayer sheet 10 while conveying the multilayer sheet 10 (step S3 ).

[0084] Here, the details of the SS-OCT apparatus 50 will be specifically described.

[0085] First, the SS-OCT device 50 measures the thickness of the multilayer sheet 10 while varying the wavelength of the radiation emitted from the radiation source 531. The wavelength is varied within a range of, for example, 1550 nm ± 100 nm. Within this range, the transmittance of the radiation through the sheet material 11 and the coating material 12 can be improved. The operation of the radiation source 531 is controlled by the computing unit 539C. The radiation from the radiation source 531 is incident on the surface of the multilayer sheet 10 from the -Z direction.

[0086] Alternatively, the wavelength of the radiation emitted from the radiation source 531 can be set to a wavelength outside the range of 1550nm ± 100nm. This can achieve high resolution when the central wavelength is shortened, while reducing scattering from the measurement object when the central wavelength is increased. Alternatively, the radiation source 531 can emit radiation that includes multiple wavelengths within the range of 1550nm ± 100nm. In this case, a single light source can emit radiation that includes multiple wavelengths, or multiple light sources capable of emitting light of different wavelengths can be used. This makes it easier to select the wavelength to be used.

[0087] The measurement light L incident on the multilayer sheet 10 is reflected (or backscattered) by the surface, interior, and backside of the multilayer sheet 10 and the inspection roller 51. The measurement light L reflected by the multilayer sheet 10 travels toward the second coupler 537. Then, in the second coupler 537, the measurement light L reflected by the multilayer sheet 10 and the reference light reflected by the reference surface 535 interfere with each other, forming interference light. The optical beat signal of the resulting interference light is detected by the Fourier transform circuit 539B of the OCT processing unit 539 via the differential amplifier 538.

[0088] The calculation unit 539C of the OCT calculation processing unit 539 performs frequency analysis on the optical beat signal of the interfering light detected by the Fourier transform circuit 539B to obtain an SS-OCT signal. The calculation unit 539C then calculates the aforementioned B-scan image based on the obtained SS-OCT signal. The calculated B-scan image is a two-dimensional representation of the reflected signal intensity distribution, as described above.

[0089] The B-scan image calculated by the calculation unit 539C is then output to the sheet generation control unit 60 along with information on the incident position of the measurement light L. At this point, as described above, the incident position of the measurement light L on the multilayer sheet 10 contacts the inspection roller 51. Therefore, the incident position of the measurement light L is stabilized against vibrations, etc. As a result, highly accurate inspection (measurement) of, for example, the thickness of the multilayer sheet 10 can be performed.

[0090] Furthermore, in the aforementioned OCT device, when infrared light with a wavelength of 1550 nm ± 100 nm is used as the measurement light L (radiated light), as described above, the measurement light L can penetrate the resin. However, when the measurement light L penetrates the resin, it generates scattered light due to fillers and other additives within the resin and the unevenness of the resin's refractive index. Furthermore, the scattered light reinforces each other, producing a random speckle pattern. This speckle pattern affects the calculation of thicknesses ΔZs and ΔZt in step S4, described later, and is therefore not preferred.

[0091] Therefore, in step S3, the thickness calculation unit 62 of the sheet generation control unit 60 performs a B-scan on the multilayer sheet 10 by emitting measurement light L from at least multiple angles. Furthermore, the thickness calculation unit 62 obtains multiple B-scan images with different speckle generation patterns and averages these B-scan images. This produces an averaged image from which speckle has been removed. The averaging process will be described later.

[0092] Next, if Figure 3 As shown, the thickness calculation unit 62 of the sheet material generation control unit 60 calculates the thickness ΔZs of the sheet material 11 and the thickness ΔZt of the coating material 12 based on the averaged image obtained in the above manner (step S4). The calculation of the thickness ΔZs and the thickness ΔZt will be described in detail later.

[0093] Next, the determination unit 63 determines whether the thickness ΔZs and thickness ΔZt calculated in step S4 are within the OK range (step S5). The OK range is the range within which the product can be considered acceptable. Specifically, the OK range is the range of thickness ΔZs and thickness ΔZt within which there are no quality issues. The OK range is pre-stored in the storage unit 64. Details of the pre-stored OK range will be described later.

[0094] At this point, if the determination unit 63 determines that the thickness ΔZs or ΔZt is not within the OK range (outside the OK range) (No in step S5), an NG signal is output to the display unit 65 (step S6). Based on the NG signal, the display unit 65 indicates that the formed multilayer sheet 10 is NG (step S7). Furthermore, the determination unit 63 associates the manufacturing number, etc., marked on the multilayer sheet 10 with the information indicating NG, and stores this information in the storage unit 64 (step S8). This allows the information stored in the storage unit 64 to be cross-referenced with the manufacturing number, etc., of the multilayer sheet 10 in subsequent steps, allowing for more reliable rejection of NG products.

[0095] On the other hand, if the determination unit 63 determines that the thickness ΔZs and the thickness ΔZt are within the acceptable range (YES in step S5 ), the operation control unit 61 determines whether the multilayer sheet 10 has been completed (step S9 ). In this case, the operation control unit 61 determines whether the multilayer sheet 10 has been completed based on information from an encoder connected to the winding roller 40 . Specifically, for example, the operation control unit 61 first calculates the number of rotations of the winding roller 40 based on the information from the encoder. It then determines whether the calculated number of rotations reaches the number pre-stored in the storage unit 64 . The pre-stored number is set to 10, for example.

[0096] At this time, if the operation control unit 61 determines that the multilayer sheet 10 is not completed (eg, less than 10 times) (No in step S9 ), the operation control unit 61 does not terminate the production of the multilayer sheet 10 but returns to step S3 and performs SS-OCT measurement again.

[0097] On the other hand, when the operation control unit 61 determines that the multilayer sheet 10 is completed (Yes in step S9) or when the process of step S8 is performed, the coating operation of the coater 33 is terminated. Then, the sheet material 11 between the sheet supply reel 20 and the coating roller 31 is cut by a cutting unit (not shown) (step S10), and the sheet production operation of the multilayer sheet 10 is terminated.

[0098] Furthermore, when performing steps S7 and S8, step S10 may be performed simultaneously. This can minimize the range of NG in the multilayer sheet.

[0099] Furthermore, the above-described steps S3 to S5 are examples of inspection steps. That is, in Embodiment 1, the inspection step is performed while the multilayer sheet 10 is being produced. This can shorten the time required from the start of production of the multilayer sheet 10 to the completion of the inspection.

[0100] <Regarding the Position of Measurement Light in the Y-Direction in Averaging Processing of Multiple B-Scan Images>

[0101] Next, use Figures 4A to 5C Come to Figure 3 The position of the measurement light in the Y direction in the averaging process of the plurality of B-scan images in step S3 shown in FIG.

[0102] Figure 4A It is a YZ plan view showing the positional relationship between the objective lens 523 of the SS-OCT apparatus 50 and the multilayer sheet 10 . Figure 4B It is an XY plan view showing the positional relationship between the inspection roller 51 of the SS-OCT apparatus 50 and the multilayer sheet 10 . Figure 5A This is a schematic diagram showing the positional relationship between the measurement light L and the multilayer sheet 10 when B scanning is performed at different B scanning positions on the inspection roller 51 but at the same B scanning position on the multilayer sheet 10 . Figure 5B This is a schematic diagram showing the positional relationship between the measurement light L and the multilayer sheet 10 when the B scan is performed at different B scan positions on the inspection roller 51 and also on the multilayer sheet 10 . Figure 5C This is a schematic diagram showing the positional relationship between the measurement light L and the multilayer sheet 10 when B scans are performed at the same B scan position on the inspection roller 51 and at different B scan positions on the multilayer sheet 10 while the conveyance speed of the multilayer sheet 10 is reduced.

[0103] When averaging multiple B-scan images, if there is variation in the thickness within the plane of the multilayer sheet 10, the speckle pattern will vary as the B-scan positions corresponding to the B-scan images differ. In this case, unlike the aforementioned averaging of the same location, B-scan images of different locations are averaged. Consequently, the accuracy of the thickness ΔZs and thickness ΔZt calculated in step S4 decreases.

[0104] Below, the sub-items (A, B, C) are Figures 5A to 5C The positional relationship between the measurement light L and the multilayer sheet 10 will be described specifically.

[0105] (A: Averaging of B-scan images obtained by B-scanning at different B-scan positions on the inspection roller and the same B-scan position on the multilayer sheet (surface))

[0106] In the first embodiment and the second embodiment described later, Figure 5A As shown, the B-scan position on the inspection roller 51 is offset by a predetermined amount parallel to the Y direction, the conveyance direction of the multilayer sheet 10. Furthermore, a B-scan image is acquired by performing a B-scan under the same conditions relative to the same B-scan position on the surface of the multilayer sheet 10 as viewed from the multilayer sheet 10. The offset amount is determined by the thickness calculation unit 62 of the sheet production control unit 60 based on the conveyance speed of the multilayer sheet 10.

[0107] Here, if Figure 4A as well as Figure 4B As shown, let r be the radius of the inspection roller 51, and let the line passing through the center of the inspection roller 51 and extending in the direction of gravity be the center line C. Furthermore, let θ1 be the angle formed by the line connecting the position on the inspection roller 51 where the measurement light L is incident during the first B scan and the center of the inspection roller 51, and the direction of gravity parallel to the Z axis (center line C). Let X1 be the distance in the horizontal direction (Y direction) from the first B scan position 51A, which is the first position of the first interference light, to the center line C. Hereinafter, a position may be referred to as "first B scan position 51A."

[0108] In this case, the radius r, the angle θ1, and the distance X1 satisfy the following formula (1).

[0109] X1=r×cosθ1 (1)

[0110] At this time, if the positional relationship between the inspection roller 51 and the measuring head 52 is fixed, the distance X1 is a known value, and thus the angle θ1 is also a known value.

[0111] Furthermore, let Δθ be the rotation angle of the inspection roller during the B-scan interval, and let X2 be the distance in the horizontal direction (Y direction) from the position on the inspection roller 51 where the measurement light L is incident during the second B-scan to the center line C. Hereinafter, this position may be referred to as the "second B-scan position 51B," which is the second interference light at the second position.

[0112] In this case, the radius r, the angle θ1, the angle Δθ, and the distance X2 satisfy the following formula (2).

[0113] X2=r×cos(θ1+Δθ) (2)

[0114] Therefore, the thickness calculator 62 controls the driver 524 to operate the galvanometer mirror pair 522 so that the first B-scan position 51A satisfies the equation (1) and the second B-scan position 51B satisfies the equation (2).

[0115] In this case, the two B-scan images obtained by the first B-scan and the second B-scan are images indicating different B-scan positions on the inspection roller 51 .

[0116] That is, Figure 5A As shown, if observed from the multilayer sheet 10, the incident position of the measuring light L on the multilayer sheet 10 (surface) is the same but the incident angle is different. Furthermore, due to the effect of the multilayer sheet 10 being bent along the arc surface 511 of the inspection roller 51, the incident angle of the measuring light L1 in the first B-scan becomes θ1, and the incident angle of the measuring light L2 in the second B-scan becomes θ2. Therefore, the speckle generation pattern of the two B-scan images is different. Therefore, the two different B-scan images are averaged. In this way, the speckle can be removed. In addition, the same measurement position is maintained on the multilayer sheet 10, so that the measurement position will not be changed. Figure 3 The calculation accuracy of the thickness ΔZs and the thickness ΔZt performed in step S4 shown above is reduced.

[0117] On the other hand, if the first and second B-scans are performed under the same conditions as above at a portion of the multilayer sheet 10 that is conveyed linearly without bending along the inspection roller 51 (e.g., a portion located between the inspection roller 51 and the coating roller 31), the incident angles of the measuring light in the two B-scan images will be equal. Consequently, the speckle patterns will also be equal. Consequently, even averaging the two obtained B-scan images will not remove the speckle. In other words, obtaining B-scan images at such portions of the multilayer sheet 10 is not a preferred method.

[0118] The B-scan position can be moved by varying the angle of the galvanometer mirror pair 522, but the present invention is not limited thereto. Alternatively, the galvanometer mirror pair 522 may be omitted and a mechanism such as a stepping motor may be provided to move the measuring head 52 itself. This arrangement allows for the same effect to be achieved without using expensive galvanometer mirrors.

[0119] (B: Average of B-scan images obtained by B-scanning at different B-scan positions on the inspection roller and also on the multilayer sheet (surface))

[0120] Furthermore, if there is no variation in the thickness within the plane of the multilayer sheet 10, the incident positions of the measurement light in multiple B-scans may vary significantly. In this case, the incident positions of the measurement light are preferably shifted significantly by, for example, a distance equal to or greater than the spot diameter of the measurement light. This can enhance the speckle reduction effect.

[0121] At this time, if Figure 5B As shown, the incident position of the measuring light L1 for the first B scan (corresponding to the first position) on the multilayer sheet 10 is set to the rear of the incident position of the measuring light L2 for the second B scan (corresponding to the second position) in the conveyance direction of the multilayer sheet 10. This arrangement allows for a significant difference in the positions of the measuring light while suppressing changes in the angle of the galvanometer mirror pair 522. Furthermore, it is possible to reliably avoid the measuring light L1 and the measuring light L2 from being incident on the same location. This arrangement allows for a significant difference in the speckle generation pattern, making it more preferable.

[0122] Alternatively, the incident position (corresponding to the second position) of the measurement light L2 of the second B scan may be positioned forward in the conveying direction of the multilayer sheet 10 relative to the incident position (corresponding to the first position) of the measurement light L1 of the first B scan. With this configuration, the same portion of the multilayer sheet 10 can be measured using measurement light incident at different angles.

[0123] Furthermore, it is preferable that the interval between the incident position of the measurement light L1 of the first B scan and the incident position of the measurement light L2 of the second B scan is the same as the distance the multilayer sheet 10 is transported from the start of the incidence of the measurement light L1 of the first B scan to the start of the incidence of the measurement light L2 of the second B scan. If this structure is used, the measurement light can be incident on the same part during the transportation of the multilayer sheet 10, and the B scan position can be set to the same. In this way, the B scan images of the same part can be averaged. As a result, it is possible to suppress the occurrence of Figure 3 The calculation accuracy of the thickness ΔZs and the thickness ΔZt performed in step S4 shown in FIG.

[0124] As described above, when performing the first B-scan and the second B-scan, Figure 5AIn the case shown, in the multilayer sheet 10, the incident angle of the measuring light is different, but the incident position is the same. Figure 5B In the case shown, both the incident angle of the measurement light (the incident angle θ1 of the measurement light L1 in the first B scan ≠ the incident angle θ2 of the measurement light L2 in the second B scan) and the incident position are different.

[0125] (C: Averaging of B-scan images obtained by B-scanning at the same B-scan position on the inspection roller and different B-scan positions on the multilayer sheet (surface))

[0126] Generally, even when there is no deviation in the thickness of the multilayer sheet 10 within the plane, continuing the B scan at the same position in the inspection roller 51 may not sufficiently remove spots due to the following conditions, etc., and is therefore not preferable.

[0127] For example, due to slack in the multilayer sheet 10 caused by disturbances or fluctuations in tension, the multilayer sheet 10 may momentarily stop or slow down during transport. In this case, there is a risk that the incident positions of the measurement light will be the same or extremely close. This may result in insufficient speckle removal, making this undesirable.

[0128] In the above situation, if Figure 5C As shown, the incident angle of the measuring light L1 in the first B-scan and the incident angle of the measuring light L2 in the second B-scan on the multilayer sheet 10 are identical. Therefore, the difference in the incident positions of the measuring light L1 and the measuring light L2 is the length obtained by multiplying the time interval between the respective B-scans by the conveying speed. Specifically, if the conveying speed approaches zero due to tension fluctuations, for example, the same speckle pattern will appear in the first and second B-scans, making this undesirable for B-scan image averaging.

[0129] In the above description of A, B, and C, two B-scan images are averaged, but the present invention is not limited to this. For example, two or more B-scan images may be averaged. This increases the measurement cycle but allows for more robust speckle pattern removal.

[0130] <Position of Measurement Light in the Y Direction in Averaging Processing of Multiple B-Scan Images of a Multilayer Sheet Having a Non-Uniform Structure in the X Direction>

[0131] Next, use Figures 6A to 6C To illustrate: Figure 3 In the averaging process of a plurality of B-scan images in step S3 shown, the position of the light in the Y direction is measured in the averaging process of the B-scan images of the multilayer sheet 10 having a structure that is non-uniform in the X direction (width direction).

[0132] Figure 6A 1 is a cross-sectional view taken along the YZ plane, illustrating the periodic structure of the sheet material 11 in the multilayer sheet 10 . Figure 6B It is an XY plan view showing the positional relationship between the inspection roller 51 of the SS-OCT apparatus 50 and the multilayer sheet 10 . Figure 6C It is an XY plan view showing the periodic structure of the sheet material 11 in the multilayer sheet 10 .

[0133] That is, even if the position in the Y direction in the multilayer sheet 10 is the same, different B-scan images may be obtained depending on the position in the X direction.

[0134] Therefore, the following, Figure 6A As shown, in order to improve the adhesion with the coating material 12 , it is considered that a periodic concavo-convex structure is provided along the X direction on the surface of the sheet material 11 .

[0135] Specifically, if Figure 6B As shown, consider the case where B-scan images are obtained at a first B-scan position 51C and a second B-scan position 51D, which are located along a line parallel to the X direction and at different positions in the Y direction. In this case, if the phase of the periodic structure in the X direction of the sheet material 11 is constant regardless of the position in the Y direction, the periodic structure in the X direction in the B-scan image will also be constant regardless of the measurement position (first B-scan position 51C and second B-scan position 51D).

[0136] However, generally speaking, regarding the conveying direction of the sheet material 11, unless a device such as an EPC (edge ​​position controller) is used, the specific phase portion of the periodic structure (such as the peak portion of the periodic structure) does not exist in the direction along the conveying direction. Figure 6C As shown, a specific phase portion P of the periodic structure may exist in a direction inclined at an angle θs in the θz direction with respect to the conveying direction.

[0137] In this case, even if the B-scan images at the first B-scan position 51C and the second B-scan position 51D are directly averaged, speckle removal can be achieved due to the different incident positions of the measurement light. However, due to the difference in the periodic structure of the sheet material 11 in the two B-scan images, the image obtained by the averaging process becomes unclear. Consequently, the calculation accuracy of the thickness ΔZs and thickness ΔZt decreases.

[0138] Therefore, Y-direction correction is performed based on the transport distance D and angle θs of the sheet material 11. Specifically, based on the transport distance D and angle θs of the sheet material 11 between the two B-scans, the second B-scan position 51D is offset in the Y direction relative to the first B-scan position 51C by a distance M that satisfies the following equation (3), allowing measurements to be made at the same position. This eliminates any phase shift in the periodic structure between the two B-scan images.

[0139] M=D×tanθs(3)

[0140] Alternatively, the angle θs may be obtained based on the phase difference between the two B-scan images in the X direction. Furthermore, the angle θs may be obtained based on the result of detecting the position of the edge of the sheet material 11 in the X direction using a displacement meter (not shown).

[0141] In addition, in the above description, the case where the phase of the surface structure of the sheet material 11 is taken into consideration is described as an example, but the present invention is not limited to this. For example, the first B-scan position 51C and the second B-scan position 51D may be adjusted as described above by taking into consideration the phase of the fiber structure of the sheet material 11 itself. In addition, even if the surface of the sheet material 11 is not a periodic structure but a non-periodic structure, the first B-scan position 51C and the second B-scan position 51D may be adjusted as described above. Furthermore, it is also possible to combine the above-mentioned Figures 4A to 4B 、 Figures 5A to 5B The adjustment of the measuring light in the multiple B scans described above and the Figures 6A to 6C The adjustment of the measurement light in the plurality of B scans described above is performed to perform averaging processing, thereby achieving the effect of removing speckles and suppressing image blur.

[0142] Correction of B-scan Images Based on the Height of the B-scan Position

[0143] Next, refer to Figure 4A as well as Figure 4B The correction of the B-scan image based on the height of the B-scan position will be described.

[0144] That is, there may be a deviation in the height in the Z direction between the first B-scan position 51A and the second B-scan position 51B. This is because the shape of the multilayer sheet 10 along the Y direction is not a straight line. If the B-scan images obtained at the first B-scan position 51A and the second B-scan position 51B at different heights are averaged, the difference in height between the first B-scan position 51A and the second B-scan position 51B is not significant. Figure 3 The calculation accuracy of the thickness ΔZs and the thickness ΔZt performed in step S4 shown above is reduced.

[0145] Therefore, the B-scan image is corrected and then averaged, thereby improving the calculation accuracy of the thickness ΔZs and the thickness ΔZt.

[0146] Specifically, in Figure 4A In the case shown, the difference H between the height of the first B-scan position 51A and the height of the second B-scan position 51B can be obtained based on the following equation (4). Therefore, the B-scan image of the second B-scan position 51B is shifted in the Z direction by an amount corresponding to the obtained difference H.

[0147] H=r×{sinθ1-sin(θ1+Δθ)} (4)

[0148] Here, for example, in an image having 100 pixels in the height direction (Z direction), in the first B-scan image, the multilayer sheet 10 is photographed at a height of the 50th pixel, and in the second B-scan image, the multilayer sheet 10 is photographed at a height of the 55th pixel due to a deviation in the Z direction by an amount corresponding to the height difference H.

[0149] In this case, the pixels in the Z direction of the second B-scan image are reduced by 5 pixels as an offset. This allows the height of the multilayer sheet 10 in the first and second B-scan images to be aligned. As a result, the calculation accuracy of the thickness ΔZs and thickness ΔZt can be improved.

[0150] In addition to the above method, a margin of 5 pixels may be provided in the height direction of the first B-scan image to make the height of the multilayer sheet 10 in the first B-scan image and the second B-scan image consistent.

[0151] Correction of B-scan Images Based on the Incident Angle of Measurement Light

[0152] Next, use Figure 7A Correction of the B-scan image based on the incident angle of the measurement light will be described. Figure 7A Schematic diagram showing the refraction state of the measurement light L in the multilayer sheet 10 .

[0153] That is, when the incident angle of the measurement light L is not perpendicular to the multilayer sheet 10, and when the refractive index of the multilayer sheet 10 is higher than that of air, correction is performed for the refraction caused in the measurement light L. Specifically, the refractive index of the coating material 12 and the sheet material 11 in the multilayer sheet 10 is slightly different, but it is much smaller than the difference in refractive index between air and the resin material.

[0154] Therefore, for simplicity, the following description will be given assuming that the multilayer sheet 10 has the same refractive index n.

[0155] For example, Figure 7A As shown, the measurement light L incident at an angle θ3 from the vertical direction, which is the thickness direction of the multilayer sheet 10, is refracted by the multilayer sheet 10 and enters the multilayer sheet 10 at an angle θ4. The optical path length of this refracted light is defined as D4.

[0156] At this time, the angle θ3 and the angle θ4 have the relationship expressed by the following formula (5).

[0157] sinθ3=n×sinθ4 (5)

[0158] In formula (5), if Figure 7A As shown, the angle θ3 is known from the relationship between the B-scan position and the position of the inspection roller 51. In addition, the refractive index n is also known. Therefore, the angle θ4 can be obtained by equation (5).

[0159] Therefore, using the refractive index n and angle θ4, the B-scan image measured by SS-OCT is multiplied by the coefficient β shown below on the Z axis.

[0160] That is, the actual thickness T of the multilayer sheet 10 can be obtained based on the following formula (6) for the obtained optical path length D4. In this case, the coefficient β becomes a value obtained by the following formula (7).

[0161] T=(D4 / n)×cosθ4 (6)

[0162] β=1 / n×cosθ4 (7)

[0163] In the above description, the B-scan position height and the B-scan image correction amount based on the incident angle of the measurement light are calculated based on the assumption that the inspection roller 51 is cylindrical, but the present invention is not limited to this. Alternatively, actual measured values, such as pixel values ​​in the depth direction of the surface and back surfaces of the multilayer sheet 10 at each B-scan position, may be used and stored in a table. Furthermore, the correction amount may be calculated based on the stored table. This allows the same effect to be achieved even if the shape of the inspection roller 51 is unknown.

[0164] <About the calculation method of thickness Z>

[0165] Next, use Figure 7B The calculation method of the thickness of the multilayer sheet will be described. Figure 7B It is an explanatory diagram of a method for calculating the thickness of the multilayer sheet 10 .

[0166] The thickness calculation unit 62 of the sheet generation control unit 60 measures the thickness of the sheet based on the obtained B-scan image. Figure 7BThe left figure shows interface positions Z1, Z2, and Z3. Interface position Z1 is the interface between air and coating material 12. Interface position Z2 is the interface between coating material 12 and sheet material 11. Interface position Z3 is the interface between sheet material 11 and the air behind it or the inspection roller 51.

[0167] Furthermore, the interface positions Z1, Z2, and Z3 can be measured, for example, using the peak position of the signal intensity in the Z direction, or using other signal processing methods such as edge detection of SS-OCT signals. In this case, filters such as integral filters can be applied in the X and Y directions to improve the accuracy of interface position measurement.

[0168] Furthermore, in the first and second embodiments described above, only the thickness ΔZs and the thickness ΔZt need to be calculated, and thus, only the interface position Z1, the interface position Z2, and the interface position Z3 need to be distinguished. Therefore, for example, it is not necessary to distinguish whether the SS-OCT signal corresponding to the interface position Z2 or the interface position Z3 originates from the sheet material 11 or the coating material 12. However, it is also possible to distinguish between the sheet material 11 and the coating material 12 by utilizing the difference in the intensity of scattered light relative to the measurement light within the sheet material 11 and the coating material 12.

[0169] Specifically, when the inside of the sheet material 11 is uniform and the inside of the coating material 12 contains a mixture, the measurement light is greatly scattered inside the coating material 12. In this case, Figure 7B As shown in the right figure, the signal intensity between interface position Z1 and interface position Z2 is stronger than the signal intensity between interface position Z2 and interface position Z3. Therefore, the difference in the obtained signal intensity can also be used to distinguish between the sheet material 11 and the coating material 12.

[0170] Furthermore, based on the obtained interface positions Z1, Z2, and Z3, (Z2-Z1) becomes the optical thickness including the refractive index of the coating material 12. Furthermore, (Z3-Z2) becomes the optical thickness including the refractive index of the sheet material 11. Therefore, these optical thicknesses are divided by the known refractive indices of the sheet material 11 and the coating material 12. This yields the respective physical thicknesses ΔZs and ΔZt. The physical thicknesses ΔZs and ΔZt here are the average thicknesses in the X direction obtained from two B scans. Alternatively, for example, the minimum and maximum thicknesses can be determined for each X-direction location in each B scan. This allows the minimum and maximum thicknesses within the range to be used as the "physical thickness," rather than simply the X-direction average.

[0171] The sheet production control unit 60 then rotates the winding roller 40 and drives the coater 33, thereby continuing the above-mentioned measurement while changing the rotation angle θ of the winding roller 40. Thus, the thickness ΔZs and the thickness ΔZt are measured at all rotation angles θ until the production of the multilayer sheet 10 is completed.

[0172] Through the above, the thickness ΔZs and the thickness ΔZt of the multilayer sheet 10 can be calculated.

[0173] <About the determination of whether multilayer sheets are acceptable>

[0174] Next, the determination of whether the produced multilayer sheet 10 is acceptable will be described.

[0175] First, when using the multilayer sheet 10 as an adhesive sheet, if the thickness ΔZt and thickness ΔZs are not above a certain value, the multilayer sheet may not function properly. Specifically, for example, if the thickness ΔZs of the sheet material 11 is too thin, the strength may be insufficient. On the other hand, if the thickness ΔZt of the coating material 12, which serves as the adhesive, is too thin, the adhesive strength may be insufficient.

[0176] Therefore, in Embodiments 1 and 2, a first threshold is used as a threshold of a certain size to determine whether the multilayer sheet is acceptable. Specifically, determination unit 63 compares the first threshold with thickness ΔZs and thickness ΔZt to determine whether the multilayer sheet is acceptable. In this case, the first threshold is set to 50 μm, for example.

[0177] On the other hand, excessively large thicknesses ΔZs and ΔZt can sometimes lead to problems. Therefore, thicknesses ΔZs and ΔZt need to be kept below a certain threshold. Therefore, a second threshold is used as a threshold to further determine whether the multilayer sheet is acceptable. For example, the second threshold is set to 100 μm.

[0178] That is, the range between the first threshold and the second threshold is set as the OK range for the multilayer sheet and stored in advance in the storage unit 64. The determination unit 63 then determines whether the multilayer sheet 10 is acceptable based on the stored OK range.

[0179] <Effects of Embodiment 1>

[0180] According to the first embodiment, the thickness ΔZs of the sheet material 11 and the thickness ΔZt of the coating material 12 are measured using an SS-OCT device 50 that utilizes interfering light. Therefore, there is no need to provide an explosion-proof cover on the measuring head 52 of the SS-OCT device 50, as in the X-ray thickness meter 93 of Patent Document 1. In other words, the measuring head 52 can be installed near the location where the coating material 12 is applied to the sheet material 11. Thus, the sheet production device 1 can simultaneously inspect the thickness of the newly produced multilayer sheet 10 while producing the multilayer sheet 10. Consequently, the cycle time from the start of production of the multilayer sheet 10 to the completion of thickness inspection of the multilayer sheet 10 can be shortened.

[0181] (Implementation Method 2)

[0182] Hereinafter, the sheet material production apparatus 1A in Embodiment 2 of the present disclosure will be described in detail.

[0183] <Schematic Structure of Sheet Production Apparatus>

[0184] First, use Figure 8 A schematic configuration of a sheet production apparatus 1A in Embodiment 2 of the present disclosure will be described.

[0185] Figure 8 Schematic diagram of sheet production apparatus 1A in Embodiment 2 of the present disclosure. Components identical to those in Embodiment 1 are denoted by the same reference numerals and names, and their description may be omitted.

[0186] like Figure 8 As shown, the sheet production apparatus 1A of the second embodiment differs from the sheet production apparatus 1 of the first embodiment in that a thickness adjustment unit 70A is further provided and a sheet production control unit 60A is provided instead of the sheet production control unit 60 .

[0187] The thickness adjustment unit 70A of the sheet production apparatus 1A includes a pair of rollers 71A that sandwich the multilayer sheet 10 , a moving device 72A that controls the positions of the pair of rollers 71A to change the thickness of the multilayer sheet 10 , and the like.

[0188] The pair of rollers 71A is provided so as to sandwich the multilayer sheet 10 between the coating roller 31 and the winding roller 40. The moving device 72A is driven to change the gap between the pair of rollers 71A. This allows the thickness of the multilayer sheet 10 to vary.

[0189] Furthermore, the sheet generation control section 60A differs from the sheet generation control section 60 of the first embodiment in that it further includes a feedback control section 66A.

[0190] Specifically, the feedback control unit 66A feeds back to the moving device 72A of the thickness adjustment unit 70A the control amounts based on the thickness ΔZs and thickness ΔZt obtained using the SS-OCT device 50. The relationship between the thickness ΔZs and thickness ΔZt and the control amounts is stored in the storage unit 64 in advance as a relational expression or table.

[0191] That is, feedback control unit 66A determines the control amount using a relational expression or table stored in advance, and feeds back the result to movement device 72A.

[0192] <Sheet production method>

[0193] Next, refer to Figure 8 While using Figure 9 A sheet production method performed by the sheet production apparatus 1A will be described. Figure 9 1 is a flowchart showing a sheet production method. In addition, the same steps as those in Embodiment 1 are sometimes denoted by the same reference numerals and their descriptions are omitted.

[0194] First, if Figure 9 As shown, Figure 3 The processing of step S1 to step S9 of the embodiment 1 shown.

[0195] Then, in step 9 , the operation control unit 61 determines whether the multilayer sheet 10 is completed. If the operation control unit 61 determines that the multilayer sheet 10 is completed (YES in step S9 ), the process of step S10 is performed.

[0196] On the other hand, when the action control unit 61 determines that the multilayer sheet 10 is not completed (No in step S9), the feedback control unit 66A calculates the control amount (feedback amount) of a pair of rollers 71A based on the calculation results of the thickness ΔZs and the thickness ΔZt in step S4 (step S21).

[0197] Then, the feedback control section 66A performs feedback to the mobile device 72A (step S22 ).

[0198] Next, the moving device 72A adjusts the gap between the pair of rollers 71A based on the feedback amount.

[0199] Thereafter, the process returns to step S3 and the SS-OCT measurement by the SS-OCT apparatus 50 is performed again.

[0200] Next, similarly to the first embodiment, the sheet material 11 between the sheet supply reel 20 and the coating roller 31 is cut by a cutting unit (not shown) (step S10 ), and the sheet production operation of the multilayer sheet 10 is completed.

[0201] (Variation)

[0202] The present disclosure is of course not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present disclosure.

[0203] For example, the following configuration can be applied to Embodiment 1 and Embodiment 2.

[0204] Specifically, in the criteria for determining whether the multilayer sheet 10 is acceptable, upper and lower threshold values ​​can be set for the sheet material 11 and the coating material 12, respectively. Thus, for example, if the thickness of the sheet material 11 fluctuates as a material characteristic, the threshold value for the coating material 12 can be strictly set compared to the upper and lower threshold values ​​for the sheet material 11, thereby achieving the effect of maintaining the thickness accuracy of the coating material.

[0205] In the above description, the actual thickness ΔZs and thickness ΔZt are obtained by dividing the optical thickness by the refractive index. However, the present invention is not limited to this. For example, the obtained optical thickness can be used directly as the thickness ΔZs and thickness ΔZt, respectively, and threshold values ​​corresponding to the thickness ΔZs and thickness ΔZt can be set. This allows for maintaining accuracy even when the refractive index of the object is unknown.

[0206] Alternatively, thickness ΔZs and thickness ΔZt can be calculated based on the results of a single B-scan (a single B-scan image), or based on the results of at least one A-scan. Furthermore, measurement light can be directed onto both sides of the multilayer sheet 10, in other words, the sheet material 11 side and the coating material 12 side, and the thickness ΔZs and thickness ΔZt can be measured using this measurement light. In this case, the above configuration can also be achieved by using two SS-OCT devices 50. This allows for obtaining a good image on the back side of the sheet material 11, even when transparency is insufficient.

[0207] In addition, in the above description, the sheet supply reel 20, the coating roller 31, and the inspection roller 51 are not provided with a separate drive source for rotating each. However, a separate rotation drive device such as a motor may be provided for each of them. This makes it easier to control the travel speed than when a single motor is used for driving.

[0208] In addition, in Embodiment 2, a configuration using a mechanism for adjusting the gap between a pair of rollers 71A as the thickness adjustment unit 70A is described as an example, but the present invention is not limited to this. Other mechanisms that have the function of adjusting or regulating the thickness of the multilayer sheet 10 in the Z-axis direction, such as a mechanism that adjusts the thickness of the multilayer sheet 10 by heating, may also be employed. Furthermore, for example, a mechanism that adjusts only the thickness of the coating material 12 by a peeling action, such as that of a scraper, may also be employed. This allows for thickness adjustment regardless of the physical properties of the coating material.

[0209] In addition, in the second embodiment, the thickness adjustment portion 70A is described as a structure in which the thickness of the multilayer sheet 10 is changed by sandwiching the multilayer sheet 10, but the present invention is not limited to this. For example, a structure in which only the sheet material 11 is sandwiched and the thickness of the sheet material 11 is changed may be used. Furthermore, a structure in which only the coating thickness of the applicator 33 is changed may be used. In this case, a structure in which the thickness of both the sheet material 11 and the coating material 12 are changed may also be used.

[0210] Furthermore, any of the above-described embodiments and modifications may be appropriately combined to achieve the effects possessed by each.

[0211] Furthermore, in Embodiments 1 and 2, speckles are generated when infrared light, used as measuring light, passes through the resin, reducing the accuracy of the detected thickness. Therefore, as described above, it is more desirable to measure the thickness of the sheet material 11 and the coating material 12 using the inspection roller 51 during the production of the multilayer sheet, but this is not a limitation. For example, it is also possible to measure the thickness of the multilayer sheet 10 using SS-OCT after completion. This allows for measurement in a more stable environment than using the inspection roller 51.

Claims

1. A sheet material production device for producing a multilayer sheet by applying a coating material to a conveyed sheet material, the sheet material production device comprising: A radiant light source that emits radiant light; a splitting portion that splits the radiated light into a measurement light that is incident on the multilayer sheet and a reference light that is irradiated on a reference surface; an interference detection unit for detecting interference light obtained by interference between the measurement light reflected by the multilayer sheet and the reference light reflected by the reference surface; a distribution acquisition unit that acquires, with respect to the length direction of the multilayer sheet, at least two interference light intensity distributions, including a first interference light intensity distribution based on measurement light at a first incident angle at a first incident position and an intensity distribution of a second interference light based on measurement light at a second incident position at a second incident angle different from the first incident angle; and The thickness calculation unit calculates the thicknesses of the sheet material and the coating material based on a result obtained by averaging the intensity distributions of the at least two interference lights.

2. The sheet material production device according to claim 1, wherein: The apparatus further comprises: an inspection roller provided to contact the multilayer sheet on the opposite side of the optical component with the multilayer sheet interposed therebetween; The inspection roller is arranged so that the central axis of the inspection roller is parallel to the width direction of the multilayer sheet. The optical member is configured to emit the measurement light toward the arcuate surface of the inspection roller that is in contact with the multilayer sheet.

3. The sheet material production device according to claim 2, wherein: The optical component is composed of an objective lens and a pair of galvanometer mirrors forming a telecentric optical system.

4. The sheet material production device according to claim 2, wherein: The optical component is configured so that the optical component itself moves along the width direction of the multilayer sheet.

5. The sheet material production device according to claim 1, wherein: The first incident position and the second incident position are the same incident position.

6. The sheet material production device according to claim 1, wherein: The intensity distribution of the first interference light and the intensity distribution of the second interference light are intensity distributions of the interference light at the same portion of the multilayer sheet.

7. The sheet material production device according to claim 1, wherein: Also features: a coater for applying the coating material to the sheet material; a winding roller for winding the multilayer sheet; and The optical component is configured to emit the measurement light toward the multilayer sheet located between the coater and the winding roller.

8. The sheet material production device according to claim 1, wherein: After acquiring the intensity distribution of the first interfering light, the distribution acquisition unit acquires the intensity distribution of the second interfering light at a second incident position that is further forward than the first incident position in the conveyance direction of the multilayer sheet.

9. The sheet material production device according to claim 1, wherein: After acquiring the intensity distribution of the first interfering light, the distribution acquisition unit acquires the intensity distribution of the second interfering light at a second incident position further rearward than the first incident position in the conveyance direction of the multilayer sheet.

10. The sheet material production device according to claim 9, wherein: The distance between the first incident position and the second incident position is the same as the distance the multilayer sheet is conveyed from the start of the measurement light incident on the first incident position to the start of the measurement light incident on the second incident position.

11. The sheet material production device according to any one of claims 1 to 10, wherein: The device further includes a thickness adjusting unit configured to adjust at least one of the thickness of the sheet material and the thickness of the coating material based on the thicknesses of the sheet material and the coating material.

12. The sheet material production device according to any one of claims 1 to 10, wherein: The radiated light is infrared light.

13. The sheet material production device according to any one of claims 1 to 10, wherein: The radiation light source emits radiation light having a wavelength within the range of 1550 nm ± 100 nm and periodically changing.

14. The sheet material production device according to any one of claims 1 to 10, wherein: The radiation light source emits radiation light including a plurality of wavelengths within a range of 1550 nm±100 nm.

15. The sheet material production device according to any one of claims 1 to 10, wherein: The invention further includes a determination unit configured to determine whether the multilayer sheet is acceptable based on the thickness of the sheet material and the coating material.

16. A method for producing a sheet material, comprising applying a coating material to a conveyed sheet material to produce a multilayer sheet material, the method comprising: the step of emitting radiation from a radiation source; a step of dividing the radiated light into measurement light and reference light; a step of emitting the measurement light toward the multilayer sheet through an optical component; irradiating the reference light onto a reference surface; detecting interference light obtained by interference between the measurement light reflected by the multilayer sheet and the reference light reflected by the reference surface; a distribution acquisition step of acquiring, with respect to the length direction of the multilayer sheet, at least two interference light intensity distributions including a first interference light intensity distribution and a second interference light intensity distribution, wherein the first interference light is based on measurement light at a first incident angle at a first incident position, and the second interference light is based on measurement light at a second incident angle different from the first incident angle at a second incident position; and The step of calculating the thicknesses of the sheet material and the coating material based on a result obtained by averaging the intensity distributions of the at least two interference lights.

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