Inspection device, inspection method, and film manufacturing method

Abstract

Provided are an inspection device, an inspection method, and a film manufacturing method that are suitable for planar inspection of the circumferential surface of a film roll.　An inspection device (10) comprises: a light source 30 that irradiates the circumferential surface of a film roll (11) with linear illumination light which is long in the width direction of a film (12); an area sensor (32) that consecutively images an area which is long in the width direction of the film (12) and which includes the irradiation range of the illumination light; and a detection part (34) that detects unevenness of the circumferential surface of the film roll (11) by using time variations in the shape of the reflected illumination light imaged by the area sensor (32).

Description

Inspection device, inspection method, and film manufacturing method

[0001] The present invention relates to an inspection device, an inspection method, and a film manufacturing method for inspecting the peripheral surface of a film roll that rotates around an axis as a long film is transported.

[0002] The following Patent Document 1 describes an inspection device that includes a light source that irradiates an object under inspection with a linear illumination light and a camera that captures an image of an area including the illumination area of ​​the illumination light. This inspection device continuously captures images while sliding the light source and camera relative to the object under inspection, and detects the angle (angle relative to the camera) of the surface of the object under inspection (the reflection point of the illumination light).

[0003] Japanese Patent Application Laid-Open No. 2016-200396

[0004] However, in the above-mentioned Patent Document 1, although it is possible to detect the inclination of the reflection point itself, it is difficult to grasp the relationship and continuity between the reflection point and adjacent parts, and there is a problem that it is not suitable for detecting surface shapes (detecting relatively small irregularities).

[0005] The present invention has been made in view of the above-mentioned background, and aims to provide an inspection device, an inspection method, and a film manufacturing method that are suitable for inspecting the surface condition of the peripheral surface of a film roll (the surface condition of the film on the peripheral surface of the film roll), which is an object to be inspected.

[0006] In order to achieve the above object, the inspection device of the present invention is an inspection device that inspects the peripheral surface of a film roll that rotates around an axis as a long film is transported, and is equipped with a light source that irradiates the peripheral surface of the film roll with a long line of illumination light in the width direction of the film, an area sensor that continuously photographs an area that is long in the width direction of the film and includes the irradiation range of the illumination light, and a detection unit that detects unevenness on the peripheral surface of the film roll using changes over time in the shape of the reflected light of the illumination light photographed by the area sensor.

[0007] The detection unit may divide the image captured by the area sensor into multiple images that are long in the film transport direction, extract the maximum brightness point from each image, and detect unevenness using the temporal change in the position of the maximum brightness point in the transport direction.

[0008] An image that is long in the film transport direction may be formed by arranging one pixel's worth of shooting range of the area sensor in the transport direction, and the detection unit may extract the maximum brightness point by taking the shooting range with the maximum brightness among the one pixel's worth of shooting range as the target range, calculating the brightness centroid point within the target range using the brightness of the shooting range adjacent to the target range in the transport direction, and extracting the brightness centroid point as the maximum brightness point.

[0009] The width of the film is within a range of 0.2 m or more and 3 m or less, and the area sensor is placed at a position separated from the film roll by a range of 1 m or more and 3 m or less, and may be a single digital camera whose shooting range includes the entire width of the film.

[0010] The detection unit may detect the shape and size of the irregularities in the transport direction by using a change over time in the position of the maximum brightness point in the transport direction.

[0011] The detection unit may be configured to determine the type of unevenness using the shape of the unevenness in the conveyance direction.

[0012] The detection unit may detect the size of unevenness in the width direction by comparing the temporal change in the maximum brightness point in the transport direction with the width direction of the film.

[0013] The detection unit may determine the type of unevenness using the ratio between the size of the unevenness in the transport direction and the size of the unevenness in the width direction.

[0014] The apparatus may further include an image forming unit for forming an inspection image in which the irregularities are displayed on a plan view of the outer periphery of the film roll.

[0015] In order to achieve the above object, the inspection method of the present invention is an inspection method for inspecting the peripheral surface of a film roll that rotates around an axis as a long film is transported, and includes an illumination step of irradiating the peripheral surface of the film roll with a long line of illumination light in the width direction of the film, an imaging step of continuously photographing an area that is long in the width direction of the film and includes the irradiation range of the illumination light, and an inspection step of detecting unevenness on the peripheral surface of the film roll using changes over time in the shape of the reflected light of the illumination light photographed in the imaging step.

[0016] Furthermore, in order to achieve the above object, the film manufacturing method of the present invention includes a film manufacturing process in which a long film is formed and transported in the form of a film roll wound around a spool; and a film transport process in which the film is unwound from the film roll and then rewound into a film roll. The film transport process includes an illumination step in which a line of illumination light that is long in the width direction of the film is irradiated onto the circumferential surface of the film roll, a photographing step in which a long area in the width direction of the film that includes the irradiated range of the illumination light is continuously photographed, and an inspection step in which unevenness of the circumferential surface of the film roll is detected using a change over time in the shape of the reflected light of the illumination light photographed in the photographing step.

[0017] According to the present invention, it is possible to provide an inspection device, an inspection method, and a film manufacturing method suitable for inspecting the surface condition of the peripheral surface of a film roll.

[0018] FIG. 1 is an explanatory diagram of an inspection device. FIG. 1 is an explanatory diagram showing how a captured image is input from an area sensor. FIG. 2 is an explanatory diagram showing how a captured image is divided. FIG. 3 is an explanatory diagram for explaining a procedure for extracting a maximum brightness point. FIG. 4 is an explanatory diagram showing a line segment detected as a shape of reflected light. FIG. 5 is an explanatory diagram for explaining a shift in a maximum brightness point. FIG. 6 is an explanatory diagram for explaining a shift in a maximum brightness point. FIG. 7 is an explanatory diagram for explaining a shift in a maximum brightness point. FIG. 8 is a flowchart showing a procedure for detecting rolled up particles. FIG. 9 is an explanatory diagram of an inspection device. FIG. 10 is an image showing an example of an inspection image. FIG. 11 is an image showing an example of an inspection image. FIG. 12 is an explanatory diagram showing an example of a thickness profile in the width direction of a film. FIG. 13 is an explanatory diagram showing an example of a thickness profile in the width direction of a film.

[0019] 1, an inspection device 10 of the present invention inspects the peripheral surface of a film roll 11 (the surface shape of a film 12 on the peripheral surface of the film roll 11). The inspection device 10 is provided in a film transport process 14 where the film 12 is transported.

[0020] The film transport process 14 includes an unwinder 20 and a winder 24. The film 12 is long and strip-shaped, with a width ranging from 0.2 m to 3 m. The film 12 is transported from the previous process (film production process) in the form of a film roll 11 wound around a core and set in the unwinder 20. The film roll 11 set in the unwinder 20 rotates around the axis of the core, thereby unwinding the film 12 from the film roll 11. The film 12 unwound from the film roll 11 is transported to the winder 24 via transport rollers 26 and 28. The film 12 transported to the winder 24 is wound around the core rotating around its axis in the winder 24, and is again formed into the film roll 11.

[0021] The inspection device 10 includes a light source 30, an area sensor 32, and a detection unit 34. In this embodiment, the inspection device 10 is disposed near the unwinder 20 to inspect the surface condition of the film 12 on the circumferential surface of the film roll 11 from which the film 12 is unwound. However, the inspection device 10 may be disposed near the winder 24 to inspect the surface condition of the film 12 on the circumferential surface of the film roll 11 from which the film 12 is wound.

[0022] The light source 30 irradiates the circumferential surface of the film roll 11 (the surface of the outermost film 12) with a long linear light beam in the axial direction of the film roll 11 (the width direction of the film 12) (illumination step). In this embodiment, the light source 30 irradiates an area of ​​the film roll 11 that is 2000 mm long in the width direction of the film 12 and 20 mm long in the transport direction (width) from a slit-shaped light-emitting portion that is 3000 mm long in the width direction of the film 12 and 20 mm long in the transport direction (i.e., the width). In this embodiment, the incident angle of the light beam from the light source 30 (the angle between the normal N to the outer periphery of the film roll 11 and the illumination optical axis L1 at the point where the illumination optical axis L1 of the light beam from the light source 30 intersects with the outer periphery of the film roll 11 (the center point of the illumination range of the illumination light)) is set to 5 degrees. Furthermore, in this embodiment, the illumination light is irradiated with a light intensity such that the illuminance at the center point of the illumination range during illumination is at least five times that during non-illumination.

[0023] The specifications of the light source 30 (specifications of the light-emitting unit, irradiation range of the illumination light, irradiation angle (incidence angle), and emission intensity) are not limited to the above examples and can be changed as appropriate. However, it is preferable that the illumination light from the light source 30 irradiates the entire width of the film 12 in the width direction. It is also preferable that the illumination light from the light source 30 irradiates a length (width) range of 1 to 50 mm in the transport direction of the film 12. Furthermore, the incidence angle is preferably within the range of 5 degrees to 45 degrees. Furthermore, the light intensity of the illumination light emitted from the light source 30 is preferably within the range of 500 to 100,000 lux as illuminance on the film surface to be observed.

[0024] The area sensor 32 is a digital camera having an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary MOS), in which a plurality of photoelectric conversion elements that accumulate electric charge according to the amount of incident light are arranged on a two-dimensional plane corresponding to each pixel position, and outputs the electric charge accumulated in each pixel (photoelectric conversion element) as an image signal during photography. Note that in this embodiment, an example will be described in which the area sensor 23 is a single digital camera, but the area sensor 23 may also be a plurality of digital cameras arranged in the width direction of the film 12.

[0025] The area sensor 32 captures a rectangular area around the outer periphery of the film roll 11, including the center of the illumination range from the light source 30 and its vicinity, that is long in the width direction of the film 12 and short in the transport direction. The area sensor 32 captures images of this area continuously in a predetermined capture cycle (photographing step). In this embodiment, the area sensor 32 is positioned 1.5 m away from the film roll 11 and captures an area of ​​2000 mm in the width direction of the film 12 and 300 mm in the transport direction. In this embodiment, the area sensor 32 has a capture angle of 5 degrees (the angle between the optical axis L2 of the area sensor 32 and the normal N). The capture cycle of the area sensor 32 is set to 200 times per second.

[0026] The specifications of the area sensor 32 (such as its location, imaging range, imaging angle, and imaging cycle) are not limited to those described above and can be modified as appropriate. However, considering the depth of field of the area sensor, the area sensor 32 is preferably located at a distance of 0.5 m to 3 m from the film roll 11. The imaging range of the area sensor 32 preferably spans the entire width of the film 12 in the width direction. Furthermore, the imaging range of the area sensor 32 in the film transport direction is preferably 10 mm to 500 mm in length (width) in the film transport direction. The imaging angle is preferably 5 degrees to 45 degrees. The imaging cycle is preferably 30 to 1,000 times per second. The imaging cycle does not need to be constant and may be variable depending on the film transport speed, the diameter of the film roll 11, and other factors. Furthermore, in order to eliminate blurring of the subject, it is also preferable to adjust the transport speed of the film 12 and the shooting cycle. Specifically, it is desirable to make the transport speed of the film 12 [mm / s] / shooting cycle [f / s] < resolution [mm / pix].

[0027] 2, a captured image 40 illuminated by the light source 30 and captured by the area sensor 32 is input to the detection unit 34. The captured image 40 includes a high-brightness portion 42 on the circumferential surface of the film roll 11 (the film 12 on the circumferential surface of the film roll 11) that has become brighter by reflecting the illumination light from the light source 30. The captured image 40 is continuously input to the detection unit 34 as the area sensor 32 continues capturing images.

[0028] When the captured image 40 is input from the area sensor 32, the detection unit 34 detects the shape of the reflected light (reflected light of the illumination light from the light source 30) that appears in the input captured image 40, i.e., the shape of the high-brightness portion 42 that has become brighter due to the reflected light.

[0029] In this detection, the detection unit 34 first divides the captured image 40 in the width direction of the film 12, as shown in Fig. 3, to generate a plurality of divided images 50 that are long in the transport direction of the film 12. In this embodiment, the detection unit 34 divides the captured image 40 into pieces each having a width equivalent to one pixel of the area sensor 32, to generate the divided images 50. That is, in this embodiment, the divided images 50 are each obtained by arranging a capturing range 52 (see Fig. 4) equivalent to one pixel of the area sensor 32 in the transport direction of the film 12 (see Fig. 4).

[0030] 4 , the detection unit 34 extracts a maximum brightness point 54 from each divided image 50. In this embodiment, the detection unit 34 defines the photographing range 52 (the photographing range of one pixel of the area sensor 32) constituting the divided image 50 as the target range 52sub, which is the photographing range 52 with the maximum image brightness, and calculates a brightness centroid (brightness centroid in the transport direction of the film 12) within the target range 52sub using the brightness of the photographing ranges 52 adjacent to the target range 52sub. Then, the detection unit 34 extracts the calculated brightness centroid as the maximum brightness point 54.

[0031] Specifically, in this embodiment, the luminance of the upper imaging range 52up and the lower imaging range 52dw of the target range 52sub is used to determine a luminance centroid line 54a indicating the luminance centroid in the conveying direction within the target range 52sub, and the midpoint of the luminance centroid line 54a is extracted as the maximum luminance point 54. For example, if the luminance of the imaging range 52up is 10 and the luminance of the imaging range 52dw is 30, and the length of the target range 52sub in the conveying direction is 1, the line segment connecting the points 0.75 from the upper end of the target range 52sub (0.25 from the lower end) becomes the luminance centroid line 54a, and the center of this line segment is extracted as the luminance centroid point (i.e., the maximum luminance point 54).

[0032] In this way, by setting the brightness centroid point within the target range 52sub as the maximum brightness point 54, more accurate inspection is possible compared to, for example, when the entire target range 52sub is used as the maximum brightness point 54. That is, since the maximum brightness point 54 is used to detect unevenness as described below, the detection accuracy decreases as the range of the maximum brightness point 54 increases, and improves as the range of the maximum brightness point 54 decreases. In this embodiment, the range of the maximum brightness point 54 can be narrowed even more precisely from the target range 52sub (the shooting range of one pixel). This enables more accurate inspection.

[0033] In particular, when a relatively large inspection object such as the film 12 (film roll 11) is inspected using a single area sensor 32, the imaging range 52 per pixel of the area sensor 32 becomes relatively large, resulting in a problem of reduced inspection accuracy. In contrast, by narrowing the range of the maximum brightness point 54 even more precisely than the imaging range 52 per pixel, as in this embodiment, the problem of reduced inspection accuracy can be prevented even when a relatively large inspection object such as the film 12 (film roll 11) is inspected using a single area sensor 32.

[0034] 5, the detecting unit 34 detects the shape of a line segment 60 that is long in the width direction of the film 12 and passes through the maximum brightness point 54 of each divided image 50 extracted as described above as the shape of the high-brightness portion 42 (i.e., the shape of reflected light) in the captured image 40. Then, the detecting unit 34 detects the unevenness of the circumferential surface of the film roll 11 (the film 12 on the circumferential surface of the film roll 11) using the temporal change in the shape of the high-brightness portion 42 (line segment 60) thus detected (detection step).

[0035] In detecting the unevenness, the detector 34 checks the shift (change in position over time) of the maximum brightness point 54 for each divided image 50. That is, the detector 34 checks the shift of the maximum brightness point 54 in the transport direction of the film 12.

[0036] As shown in Fig. 6, if the peripheral surface of the film roll 11 (the film 12 on the peripheral surface of the film roll 11) is smooth, the reflection direction of the illumination light does not change even when the film 12 is fed (moved), and the maximum brightness point 54 does not shift from its initial position. On the other hand, as shown in Figs. 7 and 8, if the peripheral surface of the film roll 11 is uneven, the reflection direction of the illumination light changes as the film 12 is fed, and the maximum brightness point 54 also shifts.

[0037] 7, the maximum brightness point 54 remains at its initial position until section A (until section A reaches the illumination range of the illumination light), then shifts downward in section A (while section A is transported through the illumination range of the illumination light), then upward in section B, and then downward in section C. After section C (after section C has passed through the illumination range of the illumination light), the maximum brightness point 54 returns to its initial position and does not shift. Also, in the case of Fig. 8, the maximum brightness point 54 remains at its initial position until section D, then shifts downward in section D and upward in section E, and after section E, the maximum brightness point 54 returns to its initial position and does not shift.

[0038] The detection unit 34 utilizes this property to detect the presence of irregularities in the illumination light irradiation position during the interval between when the maximum-brightness point 54 shifts from its initial position and when it returns to its initial position, i.e., to detect the position of the irregularities. The detection unit 34 also detects the shape of the irregularities based on the pattern of the shift of the maximum-brightness point 54. Furthermore, the detection unit 34 detects the size of the irregularities in the film 12 transport direction based on the speed of the shift of the maximum-brightness point 54 (the time required for the maximum-brightness point 54 to shift from its initial position to its return to the initial position (the number of times the area sensor 32 captures an image)), the film 12 transport speed, the area captured by the area sensor 32, etc. Furthermore, the detection unit 34 detects the size of the irregularities in the width direction of the film 12 by comparing the shift of the maximum-brightness points 54 between adjacent divided images 50.

[0039] As described above, the inspection device 10 (inspection method) of the present invention includes the light source 30 (illumination step) that irradiates the circumferential surface of the film roll 11 with a line of illumination light that is long in the width direction of the film 12, the area sensor 32 (photographing step) that continuously photographs an area that is long in the width direction of the film 12 and includes the area irradiated by the illumination light, and the detection unit 34 (inspection step) that detects irregularities on the circumferential surface of the film roll 11. In the detection step, the detection unit 34 detects irregularities using the shape of the reflected light of the illumination light, specifically, the temporal change in the maximum brightness point 54. The film production method of the present invention also includes a film production process and a film transport process, and in the film transport process, inspection (irregularity detection) is performed using the inspection device 10 (inspection method).

[0040] [Second Embodiment] In the first embodiment, the detection unit 34 detects the position, shape, and size of the irregularities, but in the second embodiment, the detection unit 34 determines the type of irregularities in addition to the position, shape, and size of the irregularities. In the descriptions of the second and subsequent embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0041] 9, the detector 34 determines that the irregularities are "rolling defects" if the irregularities have the shape shown in FIG. 7 (convex shape), the size of the irregularities in the film 12 feed direction is within the range of 0.5 mm to 10 mm, the size of the irregularities in the film 12 width direction is within the range of 0.5 mm to 10 mm, and the aspect ratio of the irregularities (the size of the irregularities in the film 12 width direction divided by the size of the irregularities in the film 12 feed direction) is 1.5 or less. "Rolling defects" are relatively small, particulate irregularities that are harmful and can cause product quality degradation.

[0042] On the other hand, the detection unit 34 determines that irregularities that do not meet the above-mentioned conditions are benign irregularities that do not affect the quality of the product. Examples of such benign irregularities include irregularities caused by steps at the joints between the films 12. Such irregularities have the shape shown in Figure 8 (step-type shape), are relatively large in size in the width direction of the film 12, and have an aspect ratio of 1.5 or more.

[0043] It is preferable to notify the user when a malignant irregularity such as a "roll" is detected. Possible notification methods include outputting a warning sound or a warning message from a speaker, or displaying a warning message on a display. Furthermore, the malignant irregularity may be highlighted in an inspection image 72 (see FIGS. 11 and 12 ) described in a third embodiment below.

[0044] [Third Embodiment] As shown in Fig. 10 , in the third embodiment, the inspection device 10 includes an image forming unit 70 in addition to the aforementioned components. As shown in Figs. 11 and 12 , the image forming unit 70 forms an inspection image 72, which displays the irregularities on the circumferential surface of the film roll 11 detected by the detection unit 34 on a plan view of the outer periphery of the film roll 11. Note that the inspection image 72 in Fig. 11 shows many wrinkles and scattered "roll-up marks," i.e., serious irregularities, indicating an undesirable state in terms of product quality. On the other hand, the inspection image 72 in Fig. 12 shows few wrinkles and no serious irregularities, indicating a good state in terms of product quality.

[0045] Displaying the irregularities on a plan view in this way facilitates inspection (detection of defects (e.g., serious irregularities)) by enabling inspection of the entire peripheral surface of the film roll 11 at a glance. Furthermore, the inspection results using the inspection image 72 thus formed can be fed back to the manufacturing and transport processes of the film 12. In other words, while checking the inspection image 72, it is easy to change the manufacturing and transport conditions of the film 12 to achieve a more optimal state (favorable for product quality).

[0046] For example, the film 12 for which the test results shown in Figure 11 were obtained was manufactured by adjusting the manufacturing conditions so that the thickness profile in the width direction of the film 12 was as shown in Figure 13. As shown in Figure 13, the film 12 had an average thickness of 40 μm, and the edge portions of the film 12 were thicker than the average thickness by about 2% (Δd). Furthermore, the thickness variation in the center of the film 12 was relatively small. However, as explained in Figure 11, the film 12 having the thickness profile shown in Figure 13 had occasional severe irregularities, which was undesirable in terms of product quality.

[0047] On the other hand, the film 12 shown in Fig. 12 was manufactured by adjusting the manufacturing conditions so that the thickness profile in the width direction of the film 12 was as shown in Fig. 14. As shown in Fig. 14, this film 12 has an average thickness of 40 μm, as in Fig. 13, and the edge portions of the film 12 are thicker than the average thickness by about 2% (Δd). However, compared to Fig. 13, the film 12 has a relatively large thickness variation across the entire width. The film 12 having the thickness profile shown in Fig. 14 obtained the inspection results shown in Fig. 12, i.e., the absence of harmful irregularities and the inspection results indicating good product quality. As described above, the thickness profile has a significant impact on the winding quality of a film roll. Even in cases where the quality of the wound film cannot be predicted by indicators such as thickness variation at first glance, or where a prediction requires testing with many different thickness patterns, the present invention allows for the visualization of the entire film roll and the understanding of winding quality. Furthermore, according to the present invention, the inspection (detection of defects (e.g., serious irregularities)) and the inspection results can be easily fed back to the manufacturing and transport processes of the film 12, which can contribute to improving product quality.

[0048] 10 Inspection device 11 Film roll 12 Film 14 Conveying process 20 Unwinder 24 Winder 26, 28 Conveying rollers 30 Light source 32 Area sensor 34 Detection unit 40 Captured image 42 High-brightness area 50 Divided image 52 Captured range (captured range of one pixel of area sensor) 52sub Target range (captured range with maximum brightness) 52up Captured range (captured range above target range) 52dw Captured range (captured range below target range) 54 Maximum brightness point 54a Brightness centroid line 60 Line segment (line segment detected as the shape of reflected light) 70 Image forming unit 72 Inspection image A to E Section L1 Illumination optical axis L2 Captured optical axis N Normal line

Claims

1. An inspection device for inspecting the peripheral surface of a film roll that rotates around an axis as a long film is transported, comprising: a light source that irradiates the peripheral surface of the film roll with illumination light in a long line in the width direction of the film; an area sensor that continuously photographs an area that is long in the width direction of the film and includes the irradiation range of the illumination light; and a detection unit that detects unevenness of the peripheral surface of the film roll using changes over time in the shape of the reflected light of the illumination light photographed by the area sensor.

2. The inspection device according to claim 1, wherein the detection unit divides the image captured by the area sensor into multiple images that are long in the transport direction of the film, extracts the point of maximum brightness from each image, and detects the unevenness using the change over time in the position of the point of maximum brightness in the transport direction.

3. The inspection device of claim 2, wherein an image long in the film transport direction is formed by arranging one pixel's worth of shooting range of the area sensor in the transport direction, and wherein the detection unit, in extracting the maximum brightness point, sets the shooting range of maximum brightness out of the one pixel's shooting range as a target range, calculates a brightness centroid point within the target range using the brightness of shooting ranges adjacent to the target range in the transport direction, and extracts the brightness centroid point as the maximum brightness point.

4. The inspection device according to claim 3, wherein the width of the film is within a range of 0.2 m or more and 3 m or less, and the area sensor is a single digital camera that is positioned at a distance from the film roll within a range of 1 m or more and 3 m or less and has a shooting range that includes the entire width of the film.

5. The inspection device according to claim 2, wherein the detection unit detects the shape and size of the irregularities in the transport direction by using a change over time in the position of the maximum brightness point in the transport direction.

6. The inspection device according to claim 5, wherein the detection unit determines the type of the unevenness using the shape of the unevenness in the transport direction.

7. The inspection device according to claim 5 or 6, wherein the detection unit detects the size of the irregularities in the width direction by comparing the change over time of the maximum brightness point in the transport direction with respect to the width direction of the film.

8. The inspection device according to claim 7, wherein the detection unit determines the type of the unevenness using a ratio between the size of the unevenness in the transport direction and the size of the unevenness in the width direction.

9. The inspection device according to claim 8, further comprising an image forming section for forming an inspection image in which the irregularities are displayed on a plan view of the outer periphery of the film roll.

10. An inspection method for inspecting the peripheral surface of a film roll that rotates around an axis as a long film is transported, comprising: an illumination step of irradiating the peripheral surface of the film roll with a long line of illumination light in the width direction of the film; an imaging step of continuously photographing an area that is long in the width direction of the film and includes the irradiation range of the illumination light; and an inspection step of detecting irregularities on the peripheral surface of the film roll using changes over time in the shape of the reflected light of the illumination light photographed in the imaging step.

11. A film manufacturing method comprising: a film manufacturing process of forming a long film and transporting it in the form of a film roll wound around a core; and a film transport process of unwinding the film from the film roll and then winding it again into the form of the film roll, the film transport process comprising: an illumination step of irradiating a circumferential surface of the film roll with illumination light in a line shape that is long in the width direction of the film; an imaging step of continuously photographing an area that is long in the width direction of the film and that includes the irradiation range of the illumination light; and an inspection step of detecting irregularities on the circumferential surface of the film roll using changes over time in the shape of the reflected light of the illumination light photographed in the imaging step.

Images