CN113646624A

CN113646624A - Inspection device, inspection method, and film manufacturing method

Info

Publication number: CN113646624A
Application number: CN202080027065.9A
Authority: CN
Inventors: 尾崎麻耶; 曾我部里惠
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2019-04-11
Filing date: 2020-03-05
Publication date: 2021-11-12
Also published as: TW202040092A; JP2020173188A; KR20210150413A; WO2020208981A1

Abstract

An inspection device according to an embodiment of the present invention includes: an inspection optical system having an illumination unit and an imaging unit for acquiring an inspection image for defect determination; and a moving mechanism that moves the film, wherein the inspection optical system is fixedly arranged independently of the moving mechanism, the moving mechanism has a mechanism that moves the film relative to the inspection optical system in a first direction different from a reference direction of the film, an imaging region (a) of the imaging section extends in a second direction different from the first direction, the reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film, a first angle (θ 1) between the reference direction and the first direction is 15 ° or more and 165 ° or less, a second angle (θ 2) between the first direction and the second direction is 15 ° or more and 165 ° or less, and the reference direction and the second direction are non-orthogonal.

Description

Inspection device, inspection method, and film manufacturing method

Technical Field

The invention relates to an inspection apparatus, an inspection method, and a film manufacturing method.

Background

In optical films such as polarizing films and retardation films, films used for battery separators, and the like, after the films are formed, defect inspection of the films is performed. As a conventional technique for inspecting a film for defects, there is a technique of patent document 1. In the technique of patent document 1, a film inspection is performed while a long film is conveyed in the longitudinal direction. Specifically, the film is inspected for defects by imaging the film with a plurality of cameras arranged in the width direction while illuminating the film with an illumination unit extending in the width direction (direction orthogonal to the length direction) of the film being conveyed in the length direction.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-70856

Disclosure of Invention

Problems to be solved by the invention

The polarizing film is formed by performing a stretching process of stretching a long film formed of a material of the polarizing film in a longitudinal direction while conveying the film in the longitudinal direction by a conveying roller. For example, foreign matter adheres to the roller surface of the above-described conveying roller for conveying a long film, and the film may be damaged by the foreign matter. When the film having the damage is subjected to stretching treatment, stripe-like defects extending in the longitudinal direction of the film are generated in the film. However, in the technique of patent document 1 in which the film is conveyed in the longitudinal direction and a defect of the film is inspected by imaging a region illuminated linearly in the width direction, the defect extending in the longitudinal direction as described above cannot be detected.

Here, although the polarizing film is taken as an example and a defect extending in the longitudinal direction is described, the same problem occurs with respect to a defect extending in the reference direction set in the film. That is, as in the technique of patent document 1, when a defect inspection is performed by linearly illuminating a film along a direction orthogonal to a reference direction (corresponding to the longitudinal direction of patent document 1) while moving the film in the reference direction and taking an image of the linearly illuminated area as an imaging area, it is difficult to detect a defect extending in the reference direction.

Accordingly, an object of the present invention is to provide an inspection method and an inspection apparatus capable of detecting a defect extending in one direction in a film, and a method for manufacturing a film including the inspection method.

Means for solving the problem

An inspection apparatus according to an aspect of the present invention (hereinafter referred to as a "first inspection apparatus") includes: an inspection optical system including an illumination unit configured to illuminate a film, and an imaging unit configured to receive light from the film illuminated by the illumination unit and acquire an inspection image for defect determination; and a moving mechanism that moves the film. The inspection optical system is fixedly disposed independently of the moving mechanism. The moving mechanism includes a mechanism for moving the film in a first direction different from a reference direction of the film with respect to the inspection optical system. The imaging region of the inspection optical system extends in a second direction different from the first direction. The reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film. A first angle between the reference direction and the first direction is 15 ° or more and 165 ° or less. A second angle between the first direction and the second direction is 15 ° or more and 165 ° or less. The reference direction is not orthogonal to the second direction.

In the first inspection apparatus, the inspection image is acquired while moving the film in a first direction different from the reference direction with respect to the inspection optical system. The second direction, which is the extending direction of the imaging region of the inspection optical system, is different from the first direction and is not orthogonal to the reference direction. Therefore, a defect extending in the reference direction can be detected. In the first inspection apparatus, since the inspection optical system does not move and the film moves, the positional displacement between the illumination unit and the imaging unit does not occur in the positional relationship therebetween. Therefore, the above-described defects are easily and reliably detected.

In one embodiment of the first inspection apparatus, the inspection optical system may be a scattering optical system. When the inspection optical system is a scattering optical system, the positional accuracy of the illumination unit and the imaging unit tends to affect the detection sensitivity. When the inspection optical system is fixed and the film is moved, as described above, the positional displacement of the illumination unit and the imaging unit does not occur in the positional relationship therebetween. Therefore, the above-described defects are easily and reliably detected.

In one embodiment of the first inspection apparatus, the moving mechanism may further include a mechanism for moving the film in a third direction, which is different from the first direction and is orthogonal to the thickness direction, with respect to the inspection optical system. A third angle between the first direction and the third direction may be 15 ° or more and 165 ° or less. In this case, the inspection range in which the film is moved in the first direction to be inspected can be changed.

Another inspection apparatus according to an aspect of the present invention (hereinafter referred to as a "second inspection apparatus") includes: an inspection optical system including an illumination unit configured to illuminate a film, and an imaging unit configured to receive light from the film illuminated by the illumination unit and acquire an inspection image for defect determination; and a moving mechanism that moves at least one of the film and the inspection optical system. The moving mechanism includes a mechanism for moving one of the film and the inspection optical system in a first direction different from a reference direction of the film with respect to the other direction. The imaging region of the inspection optical system extends in a second direction different from the first direction. The reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film. A first angle between the reference direction and the first direction is 15 ° or more and less than 90 ° or greater than 90 ° and 165 ° or less. A second angle between the first direction and the second direction is 15 ° or more and 165 ° or less. The reference direction is not orthogonal to the second direction.

In the second inspection apparatus, the inspection image is acquired while moving one of the film and the inspection optical system relative to the other in a first direction different from a reference direction of the film. The second direction, which is the extending direction of the imaging region of the inspection optical system, is different from the first direction and is not orthogonal to the reference direction. Therefore, a defect extending in the reference direction can be detected.

In one embodiment of the second inspection apparatus, the moving mechanism may further include a mechanism that moves one of the film and the inspection optical system in a third direction that is different from the first direction with respect to the other direction and is orthogonal to the thickness direction. A third angle between the first direction and the third direction may be 15 ° or more and 165 ° or less. In this case, the inspection range in which the inspection is performed by moving one of the film and the inspection optical system in the first direction relative to the other can be changed.

One embodiment of each of the first inspection apparatus and the second inspection apparatus may further include a transport mechanism for transporting the film in the reference direction. The moving mechanism may move the film by moving the conveying mechanism.

An inspection method according to another aspect of the present invention (hereinafter referred to as a "first inspection method") is an inspection method for acquiring an inspection image of a film for defect determination and inspecting the film, and includes an inspection image acquisition step of acquiring an inspection image for defect determination by imaging the film by an imaging unit included in an inspection optical system while illuminating the film by an illumination unit included in the inspection optical system. In the inspection image obtaining step, the inspection image is obtained while moving the film relative to the inspection optical system in a first direction different from a reference direction of the film. The imaging region of the inspection optical system extends in a second direction different from the first direction. The reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film. A first angle between the reference direction and the first direction is 15 ° or more and 165 ° or less. A second angle between the first direction and the second direction is 15 ° or more and 165 ° or less. The reference direction is not orthogonal to the second direction.

In the first inspection method, the inspection image is acquired while moving the film in a first direction different from the reference direction with respect to the inspection optical system. The second direction, which is the extending direction of the imaging region of the inspection optical system, is different from the first direction and is not orthogonal to the reference direction. Therefore, a defect extending in the reference direction can be detected. In the first inspection method, the film is moved without moving the inspection optical system, and therefore, the positional deviation between the illumination unit and the imaging unit does not occur in the positional relationship therebetween. Therefore, the above-described defects are easily and reliably detected.

In one embodiment of the first inspection method, the inspection optical system may be a scattering optical system. When the inspection optical system is a scattering optical system, the positional accuracy of the illumination unit and the imaging unit tends to affect the detection sensitivity. Since the inspection optical system is fixed, when the film is moved, the positional displacement of the illumination unit and the imaging unit does not occur in the positional relationship therebetween as described above. Therefore, the above-described defects are easily and reliably detected.

Another inspection method (hereinafter, referred to as a "second inspection method") according to another aspect of the present invention is an inspection method for acquiring an inspection image of a film for defect determination and inspecting the film, and includes an inspection image acquisition step of acquiring an inspection image for defect determination by imaging the film by an imaging unit included in an inspection optical system while illuminating the film by an illumination unit included in the inspection optical system. In the inspection image obtaining step, an inspection image is obtained while moving one of the film and the inspection optical system relative to the other in a first direction different from a reference direction of the film. The imaging region of the inspection optical system extends in a second direction different from the first direction. The reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film. A first angle between the reference direction and the first direction is 15 ° or more and less than 90 ° or greater than 90 ° and 165 ° or less. A second angle between the first direction and the second direction is 15 ° or more and 165 ° or less. The reference direction is not orthogonal to the second direction.

In the second inspection method, an inspection image is acquired while moving one of the film and the inspection optical system relative to the other in a first direction different from a reference direction of the film. The relationship between the first angle and the second angle satisfies the relationship and the reference direction is not orthogonal to the second direction. Therefore, a defect extending in the reference direction can be detected.

In one embodiment of each of the first inspection method and the second inspection method, a range changing step of changing an inspection range of the film based on the inspection image obtaining step may be provided. The inspection image obtaining step and the range changing step may be alternately performed until the inspection images of all the inspection ranges preset in the film are obtained. This enables inspection of the entire inspection range.

In the range changing step according to one embodiment of each of the first and second inspection methods, the inspection range may be changed by moving the film in a third direction orthogonal to the thickness direction while being different from the first direction. Alternatively, in the range changing step according to an embodiment of each of the first inspection method and the second inspection method, the inspection range may be changed by conveying the film in the reference direction.

In one embodiment of each of the first inspection apparatus, the second inspection apparatus, the first inspection method, and the second inspection method, the film may be a long film. The reference direction may be a longitudinal direction of the film.

In one embodiment of each of the first inspection apparatus, the second inspection apparatus, the first inspection method, and the second inspection method, the film may include an extended film extending in one direction. The reference direction may be an extending direction of the extended film.

The present invention also relates to a method for producing a film having a step of inspecting the film by the above-described inspection method.

Effect of invention

According to the present invention, it is possible to provide an inspection apparatus and an inspection method capable of detecting a defect extending in one direction in a film, and a film manufacturing method including the inspection method.

Drawings

Fig. 1 is a flowchart of an example of a film manufacturing method including an inspection method according to an embodiment.

Fig. 2 is a diagram for explaining a film forming step included in the film manufacturing method shown in fig. 1.

Fig. 3 is a diagram for explaining defects detected in the film inspection step included in the film manufacturing method shown in fig. 1.

Fig. 4 is a schematic view of an example of an inspection apparatus for performing a film inspection process included in the film manufacturing method shown in fig. 1.

Fig. 5 is a schematic view of the inspection apparatus shown in fig. 4 when viewed from the side of the imaging unit.

Fig. 6 is a diagram for explaining a relationship among the reference direction, the first movement direction (first direction), and the extending direction of the imaging region (second direction).

Fig. 7 is a flowchart of an example of the film inspection process shown in fig. 1.

Fig. 8 is a diagram for explaining the inspection image acquisition process shown in fig. 7.

Fig. 9 is a diagram showing a range of inspection in the inspection image acquisition step shown in fig. 7.

Fig. 10 is a diagram showing an example of an inspection image obtained by inspecting a film having a defect by the first reference inspection method.

Fig. 11 is a diagram showing an example of an inspection image obtained by inspecting the film captured in fig. 10 by the second reference inspection method.

Fig. 12 is a diagram for explaining an example of an inspection apparatus used in the film inspection process of modification 1.

Fig. 13 is a schematic view of the inspection apparatus shown in fig. 12 when viewed from the side of the imaging unit.

Fig. 14 is a diagram for explaining an example of an inspection apparatus for carrying out the film inspection process of modification 2.

Fig. 15 is a diagram for explaining the relationship among the reference direction, the first movement direction (first direction), the extending direction of the imaging region (second direction), and the second movement direction (third direction) in modification 3.

Fig. 16 is a diagram for explaining an example of an inspection apparatus for carrying out the film inspection process of modification 3.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted. The dimensional ratios in the drawings do not necessarily correspond to the dimensional ratios illustrated.

Fig. 1 is a flowchart showing a film manufacturing method including an inspection method according to an embodiment. The film manufacturing method includes a film forming step S10 and a film inspecting step S20. In the present embodiment, the film produced by the film production method is a polarizing film. An example of the material of the polarizing film is a polyvinyl alcohol resin. An example of the Polyvinyl Alcohol resin is a PVA (Polyvinyl Alcohol) resin. Hereinafter, a case of manufacturing a polarizing film using a long polyvinyl alcohol resin film will be described.

In the film forming step S10, as shown in fig. 2, the polarizing film 3 is formed while the long polyvinyl alcohol resin film 2 is transported in the longitudinal direction in a roll-to-roll manner. Specifically, the long polyvinyl alcohol resin film 2 provided on the unwinding roll R1 is unwound. The unwound polyvinyl alcohol resin film 2 is conveyed by a plurality of conveying rollers R2, subjected to various processes to form a polarizing film 3, and then wound by a winding roller R3. Fig. 2 illustrates a case where the stretching process is performed in the stretching apparatus 4 disposed on the conveyance path of the polyvinyl alcohol resin film 2 among various processes. In the stretching apparatus 4, the polyvinyl alcohol resin film 2 conveyed in the longitudinal direction is stretched in the longitudinal direction. The stretching method in the stretching apparatus 4 may be either a dry or wet stretching method. Thereby, the polyvinyl alcohol resin film 2 is provided with linearly polarized light characteristics, and the polarizing film 3 is formed. Thus, the polarizing film 3 is an extended film. The extending direction of the polarizing film 3 is the longitudinal direction of the long polarizing film 3.

The film forming step S10 may include other processes for forming the polarizing film 3 (for example, a dyeing process for adsorbing a dichroic dye to the polyvinyl alcohol resin film 2, a cleaning process, a drying process, and the like).

In the film inspection step S20, the polarizing film 3 formed in the film formation step S10 is inspected for the presence or absence of defects. The inspection target in the film inspection step S20 is, for example, a long film in which portions cut out from the polarizing film 3 for inspection are connected. For example, the film to be inspected may be a long film cut out from one of both ends in the longitudinal direction of the polarizing film 3. The film to be inspected may be, for example, a film obtained by cutting out certain portions including one end (one end in the longitudinal direction) and the other end (the other end in the longitudinal direction) of each of the plurality of polarizing films 3 formed in the film forming process S10 and connecting the cut-out portions. In this case, the plurality of polarizing films 3 can be inspected for defects. The film to be inspected has a length in the longitudinal direction of 70mm to 7000mm, and has a length in the width direction orthogonal to the longitudinal direction of 50mm to 1500 mm.

As shown in fig. 3, the defect detected in the film inspection step S20 is a stripe-shaped defect 5 extending in one direction in the film 1 to be inspected. Defect 5 can be considered as: for example, a defect in which a foreign substance adhered to the surface of the conveying roller R2 used in the film forming step S10 causes damage due to stretching in the longitudinal direction by stretching treatment or tension applied to the polyvinyl alcohol resin film 2 for conveyance by the conveying roller R2. Therefore, the extending direction of the defect 5 coincides with the longitudinal direction of the polarizing film 3 formed in the film forming process S10, and coincides with the longitudinal direction of the film 1 as the inspection object. The longitudinal direction of the polarizing film 3 is the transport direction of the polarizing film 3 (or the polyvinyl alcohol resin film 2) in the film forming step S10, and is also the extending direction of the polarizing film 3. Hereinafter, the longitudinal direction of the film 1 is referred to as a reference direction D1 set in the film 1. Examples of the length of the defect 5 in the reference direction D1 are 0.2mm to 1mm, and examples of the length in the width direction orthogonal to the reference direction D1 are 0.05mm to 0.2 mm.

The inspection apparatus 10 used in the film inspection step S20 will be described with reference to fig. 4 and 5. The inspection apparatus 10 includes: a conveying mechanism 11 that conveys the film 1 in the longitudinal direction; an inspection optical system 12 that photographs the film 1; and a moving mechanism 13 that moves the conveying mechanism 11.

The transport mechanism 11 includes an unwinding roller 111, a transport roller 112, a transport roller 113, and a winding roller 114. The

rotation shafts

111a, 112a, 113a, and 114a (see fig. 5) of the unwinding roller 111, the transport roller 112, the transport roller 113, and the winding roller 114 are rotatably supported by a pair of mounts 115 fixed to the moving mechanism 13. In fig. 4, a mount 115 is schematically shown by a broken line to show a transport system of the film 1 by the transport mechanism 11 and the inspection optical system 12. The film 1 in a roll form provided on the unwinding roller 111 is conveyed to the winding roller 114 by the conveying roller 112 and the conveying roller 113, and wound in a roll form by the winding roller 114. In the embodiment shown in fig. 4, the film 1 is conveyed horizontally between the conveying roller 112 and the conveying roller 113.

The inspection optical system 12 is fixedly disposed between the conveyance roller 112 and the conveyance roller 113 independently of the movement mechanism 13. As shown in fig. 5, the inspection optical system 12 has an illumination section 121 and an imaging section 122 to image an imaging area a extending in one direction. Hereinafter, the extending direction (second direction) of the imaging area a is referred to as an extending direction D2. In fig. 5, the imaging unit 122 is not shown. An example of the illumination unit 121 and the imaging unit 122 will be described.

As shown in fig. 4, the illumination unit 121 is disposed on one surface of the film 1 (the lower surface of the film 1 in fig. 4) and illuminates the film 1. Specifically, the illumination unit 121 illuminates the imaging area (field of view) a. Therefore, the illumination unit 121 extends in the extending direction D2 of the imaging area a.

The illumination unit 121 includes a light source 121a and a light shielding body 121 b. The light source 121a extends in the extending direction of the illumination unit 121 (the extending direction D2 of the imaging area a). The light source 121a illuminates the film 1, and thus outputs light that does not affect the composition and properties of the film 1. Examples of the light source 121a are a metal halide lamp, a halogen transmission lamp, a fluorescent lamp, and the like. The light-shielding body 121b is disposed between the light source 121a and the film 1. The light-shielding body 121b functions as a knife edge for shielding a part of the light output from the light source 121a to the film 1. The light-shielding body 121b is disposed so as to hide a part (for example, half) of the illumination area of the film 1 when the light-shielding body 121b is not disposed in the direction orthogonal to the extending direction of the light source 121a when viewed from the imaging section 122.

In the configuration of the illumination unit 121, the film 1 is illuminated by the scattered light that is output from the light source 121a and scattered at the edge portion of the light-shielding body 121 b. In this way, since the film 1 is illuminated with the scattered light, the inspection optical system 12 is a scattering optical system. Since the light source 121a and the light-shielding body 121b extend in the extending direction D2 of the imaging area a, the illumination area of the film 1 by the illumination section 121 also extends in the extending direction D2.

The imaging unit 122 receives light from the film 1 illuminated by the illumination unit 121, and images the film 1 to obtain an inspection image for defect determination. The imaging unit 122 has a plurality of pixels arranged along the extending direction D2 of the imaging area a. Examples of the photographing section 122 include a CCD camera, a CMOS camera, a line sensor, and an area sensor. The imaging unit 122 is configured to capture an illumination area of the illumination unit 121 in the imaging area a.

The imaging unit 122 is electrically connected to the analysis device 14. The imaging unit 122 inputs the imaging data to the analysis device 14. The analysis device 14 sets and controls conditions of the operation in the imaging unit 122. The analysis device 14 generates an inspection image for determining the presence or absence of the defect 5 based on the imaging data from the imaging unit 122, and displays the inspection image on the display device 15. Thereby, in the case where the defect 5 is included in the film 1, the defect 5 is displayed in the inspection image. As a result, the presence or absence of defect 5 in film 1 can be determined. In order to clearly show the defect 5 when the inspection image is generated, the analysis device 14 may specify the position of the defect 5 based on the intensity of light incident on the imaging unit 122, for example, and display the defect 5 and other portions in different colors, or may distinguish the defect 5 from other portions by shading when a black-and-white image is generated. The analysis device 14 is a computer device having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, and the like. The analysis device 14 may have an imaging unit 122 for example to form the inspection image.

The analyzer 14 also functions as a control device for controlling the inspection device 10. For example, the analysis device 14 sets and controls the conveyance speed in the conveyance mechanism 11. The analysis device 14 may be a part of the inspection device 10.

The moving mechanism 13 is a mechanism that moves the film 1 in a first moving direction (first direction) D3 different from the reference direction (conveying direction) D1 of the film 1. The moving mechanism 13 includes a base plate 131 and a moving stage 132, and is a 1-axis table for electrically moving the moving stage 132 with respect to the base plate 131 in the first moving direction D3. The conveyance mechanism 11 (specifically, the gantry 115) is fixed to the movable stage 132. Accordingly, with the movement of the moving table 132, the conveying mechanism 11 moves in the first moving direction D3, and thus the film 1 moves in the first moving direction D3.

The moving mechanism 13 has a guide portion 133 extending in the first moving direction D3 between the base plate 131 and the moving stage 132, for example. In this case, for example, the movable stage 132 may be attached to the guide section 133 so as to be movable along the guide section 133. The moving mechanism 13 can have, for example, an actuator mechanism, a rack and pinion mechanism, or the like in order to move the moving stage 132 relative to the base plate 131.

The analysis device 14 may control the movement timing, the movement speed, the movement amount, and the like of the moving stage 132 included in the moving mechanism 13.

The movement of the film 1 in the first movement direction D3 by the movement mechanism 13 includes a case where the film 1 is moved in a first positive direction along the first movement direction D3 and a case where the film 1 is moved in a first reverse direction opposite to the first positive direction along the first movement direction D3.

A relationship among the reference direction D1 of the film 1, the extending direction D2 of the imaging region a, and the first moving direction D3 will be described with reference to fig. 6. The reference direction D1, the extending direction D2 of the imaging region a, and the first moving direction D3 are directions orthogonal to the thickness direction of the film 1, and have the relationship shown in fig. 6.

As shown in fig. 6, the first moving direction D3 is inclined with respect to the reference direction D1 of the film 1. The first angle θ 1 between the reference direction D1 and the first moving direction D3 is 15 ° or more and 165 ° or less. The first angle θ 1 is, for example, 45 ° or more and 135 ° or less. The first angle θ 1 is an angle between the reference direction D1 and the first moving direction D3 which increases in accordance with the rotation of the first moving direction D3 in a given rotation direction (right rotation in fig. 6) with respect to the reference direction D1 under the assumption that the reference direction D1 and the first moving direction D3 coincide with each other.

The extending direction D2 of the photographing region a is inclined with respect to the first moving direction D3 and is non-orthogonal to the reference direction D1. A second angle θ 2 between the extending direction D2 and the first moving direction D3 is 15 ° or more and 165 ° or less. The second angle θ 2 is, for example, 45 ° or more and 135 ° or less. The second angle θ 2 is an angle between the extending direction D2 and the reference direction D1 in the above angular range. The second angle θ 2 is an angle between the first moving direction D3 and the extending direction D2, which is increased in accordance with the rotation of the extending direction D2 in the predetermined rotating direction (the right rotation in fig. 6) with respect to the first moving direction D3 when the first moving direction D3 is temporarily aligned with the extending direction D2 of the photographing region a. In the present specification, the nonorthogonal relationship between the extending direction D2 and the reference direction D1 is not limited to the case where the angle between the extending direction D2 and the reference direction D1 is different from 90 °, and includes, for example, the case where the angle is in the range of 85 ° to 95 ° or is different from the range of 75 ° to 105 ° among 0 ° to 180 °. Therefore, the angle formed by the extending direction D2 and the reference direction D1 may be, for example, an angle different from the range of 85 ° to 95 ° or the range of 75 ° to 105 ° among 0 ° to 180 °. The angle formed by the extending direction D2 and the reference direction D1 is also an angle between the reference direction D1 and the extending direction D2, which increases when the extending direction D2 is rotated in the predetermined rotating direction (for example, right rotation in fig. 6) with respect to the reference direction D1 from the case where the reference direction D1 and the extending direction D2 coincide with each other.

Next, a film inspection process S20 using the inspection apparatus 10 will be described. Fig. 7 is a flowchart of an example of the inspection process. In the film inspection step S20, the film 1 to be inspected is set on the unwinding roller 111, and the film 1 is unwound. The film 1 thus discharged is wound around a winding roller 114 via a conveying roller 112 and a conveying roller 113. The case where the film 1 is provided in this manner and then the film inspection is performed will be described. The film inspection step S20 includes an inspection image acquisition step S21, a determination step S22, and a range change step S23.

First, in a state where the conveyance of the film 1 by the conveyance mechanism 11 is stopped, the moving stage 132 is moved by the movement mechanism 13, and the film 1 is imaged by the inspection optical system 12 which is fixedly arranged (that is, does not move) while the film 1 is moved in the first movement direction D3 (for example, the first forward direction), as shown by the solid line and the two-dot chain line in fig. 8. Specifically, the film 1 is irradiated with light from the illumination unit 121, and the film 1 is imaged by the imaging unit 122. The imaging data obtained by the imaging unit 122 is input to the analysis device 14, and the analysis device 14 generates an inspection image (an inspection image obtaining step S21 in fig. 7). The inspection image generated by the analysis device 14 is displayed on the display device 15.

In the inspection image obtaining step S21, the film 1 is moved in the first moving direction D3 by the moving mechanism 13, for example, until the entire width direction of the film 1 is captured. Thereby, as indicated by hatching in fig. 9, image data of the inspection range B in the film 1 can be obtained. The length of the inspection range B in the conveying direction substantially corresponds to the length of the imaging area a in the conveying direction (the distance in the conveying direction between the upstream end and the downstream end of the imaging area a).

Depending on the size of the film 1, the inspection image acquisition step S21 is performed in a range where the film 1 can be inspected. That is, in the inspection image obtaining step S21, a part of the film 1 is inspected. Therefore, when the movement of the film 1 by the moving mechanism 13 is completed (that is, the inspection image obtaining step S21 is completed), it is determined whether or not the inspection of the film 1 in the desired entire inspection range (the predetermined entire inspection range) is completed (determination step S22 in fig. 7). The determination can be performed, for example, by comparing the size of the inspection end range calculated based on the number of times the inspection image obtaining step S21 is performed and the size of the inspection range B with the size of the desired entire inspection range in the film 1 by the analyzer 14. Alternatively, the operator may visually confirm the result.

If the inspection of the desired entire inspection range is not completed (no in the determination step S22), the inspection range to be inspected in the inspection image acquisition step S21 is changed (range changing step S23 in fig. 7). In the range changing step S23, the film 1 is conveyed in the reference direction D1 (conveying direction). The conveying amount is substantially equal to the length of the inspection range B in the conveying direction. When the inspection of the desired entire inspection range is completed (yes in determination step S22), the inspection is completed.

In the film inspection step S20, the inspection image acquisition step S21 and the range change step S23 are performed until all of the desired entire inspection ranges in the inspection film 1 are inspected. When the inspection image obtaining step S21 is performed a plurality of times by repeating the inspection image obtaining step S21 and the inspection range changing step S22, the case where the moving stage 132 is moved in the first forward direction on the first moving direction D3 by the moving mechanism 13 and the case where the moving stage 132 is moved in the first reverse direction may be alternately performed in the plurality of inspection image obtaining steps S21.

If the inspection image of the film 1 obtained by performing the film inspection step S20 shows a defect 5, foreign matter may adhere to any of the conveyance rollers R2 (particularly, rollers before the stretching process) used in the film formation step S10. Therefore, the roller surface of the conveying roller R2 used in the film forming process S10 may be cleaned or the conveying roller R2 may be replaced. Thereby, the polarizing film 3 containing no defect 5 can be manufactured.

In inspecting the film, consider the following: the imaging unit 122 and the illumination unit 121 are disposed so that the extending direction D2 of the imaging area a is orthogonal to the reference direction D1, and the film is imaged while being conveyed in the conveying direction (hereinafter, referred to as "first reference inspection method"). However, in the above-described first reference inspection method, even if the film having the defect 5 is inspected, as shown in fig. 10, the defect 5 is not displayed in the inspection image obtained by photographing the film. That is, the defect 5 is not detected. On the other hand, when the extending direction D2 of the imaging region a is directed in a direction different from the reference direction D1 and 90 ° (when the extending direction D2 is not orthogonal to the reference direction D1), the film is imaged while being conveyed in the reference direction D1 (hereinafter, referred to as "second reference inspection method"), and the defect 5 is detected as appearing in the region indicated by the broken line in fig. 11. This is considered to be because, in the second reference inspection method, the defect 5 is illuminated with more light than in the case of the first reference inspection method, and as a result, the amount of light incident on the imaging section becomes larger.

The ring-shaped marks shown in fig. 10 and 11 are marks showing regions where the defects 5 are formed in the film. Fig. 10 and 11 are diagrams showing the results of imaging the same film having the defect 5 formed at the position of the annular mark under the same conditions except for the point where the orientation of the imaging area a with respect to the reference direction D1 is tilted as described above.

In the film inspection method using the inspection apparatus 10, in the inspection image acquisition step S21, the film 1 is imaged by the inspection optical system 12 while the film 1 is moved in the first movement direction D3. In the present embodiment, the extending direction D2, the reference direction D1, and the first moving direction D3 of the imaging area a have the relationship shown in fig. 6, and as described above, the reference direction D1 and the extending direction D2 are not orthogonal. As a result, in the film inspection method using the inspection apparatus 10, the defect 5 can be detected in the same manner as in the second reference inspection method.

Since the film 1 is moved in the first moving direction D3, an inspection image of the film 1 can be obtained even if there is one inspection optical system 12, for example. Further, since the inspection optical system 12 is fixedly disposed and the film 1 is moved independently of the inspection optical system 12, the positional relationship between the imaging unit 122 and the illumination unit 121 does not vary. As a result, the defect 5 can be reliably detected. As shown in fig. 4, when light is scattered by the light-shielding member 121b and the film 1 is illuminated with the scattered light, the positional accuracy of the imaging unit 122 and the illumination unit 121 is very important. Therefore, the inspection apparatus 10 and the inspection method using the same are very effective in the case where the film 1 is illuminated by the scattered light output from the illumination unit 121.

Next, various modifications of the above embodiment will be described focusing on differences from the above embodiment.

(first modification)

The film inspection step S20 is performed on the film 1 obtained by winding the polarizing film 3 into a roll shape at one time in the film formation step S10 and then cutting a predetermined region from the formed polarizing film 3. However, as shown in fig. 12, the polarizing film 3 formed in the film forming step S10 may be further conveyed by a conveying roller R2, and the polarizing film 3 may be subjected to a film inspecting step S20. In other words, the film inspection step S20 may be performed before the polarizing film 3 formed in the film forming step S10 is wound into a roll shape.

Fig. 12 and 13 are schematic diagrams of the inspection apparatus 20 used in the film inspection step S20 according to modification 1. The inspection apparatus 20 includes an inspection optical system 12, a moving mechanism 13, and a conveying mechanism 21. The configurations of the inspection optical system 12 and the moving mechanism 13 are the same as those of the inspection apparatus 10, and therefore, the description thereof is omitted.

The conveying mechanism 21 includes a winding roller 211, a conveying roller 212, and a pair of stands 213. The winding roller 211 is a roller for winding the polarizing film 3 in a roll shape. The transport roller 212 is a roller that guides and supports the polarizing film 3 in order to transport the polarizing film 3 to the winding roller 211. The pair of mounts 213 rotatably support the

rotation shafts

211a and 212a of the winding roller 211 and the conveying roller 212, respectively. The pair of mounts 213 are fixed to the moving mechanism 13 (specifically, the moving stage 132). In the embodiment shown in fig. 12, the winding roller 211 and the conveying roller 212 are configured to convey the polarizing film 3 substantially horizontally therebetween.

The film inspection step S20 of the first modification includes an inspection image acquisition step S21, a determination step S22, and a range change step S23 shown in fig. 7, as in the case of the inspection apparatus 10. The inspection image obtaining step S21, the determination step S22, and the range changing step S23 are the same as the inspection image obtaining step S21, the determination step S22, and the range changing step S23 included in the film inspection step S20 using the inspection apparatus 10, except that the inspection target is the polarizing film 3 itself.

In modification 1, substantially the entire polarizing film 3 may be an inspection range. However, for example, in the conveying direction of the polarizing film 3, a plurality of regions set discretely may be inspection ranges, respectively.

In modification 1, in the inspection image obtaining step S21, the polarizing film 3 is moved by the moving mechanism 13, and the conveyance of the polarizing film 3 is stopped. Therefore, as shown in fig. 12, an accumulator 22 is disposed in a front stage of the inspection apparatus 20. The accumulator 22 is a mechanism for separately controlling the transport speed of the polarizing film 3 up to the accumulator 22 and the transport speed after the accumulator 22 (including the case where the transport speed is 0).

As shown in fig. 12, the accumulator 22 includes a fixed roller 221 and a movable roller 222 capable of adjusting a distance from the fixed roller 221. In the accumulator 22, the conveying distance of the polarizing film 3 is changed by moving the position of the movable roller 222. This enables adjustment of the subsequent transfer speed of the accumulator 22. For example, by moving the movable roller 222 so as to increase the transport distance of the polarizing film 3 between the fixed roller 221 and the movable roller 222, the polarizing film 3 is retained in the accumulator 22, and therefore the transport speed (speed 0 depending on the retention time) of the polarizing film 3 after the accumulator 22 can be reduced. The position of the movable roller 222 may be controlled by the analyzer 14, for example. The accumulator 22 may also be part of the inspection device 20.

In the inspection image obtaining step S21, the transport mechanism 11 is moved in the first movement direction D3 with respect to the inspection optical system 12 by the movement mechanism 13, and thereby the polarizing film 3 is moved in the first movement direction D3 with respect to the inspection optical system 12. Therefore, a steering rod (conveying direction changing unit) 23 may be disposed between the accumulator 22 and the conveying roller 212 of the inspection apparatus 20. The steering rod 23 functions as a conveyance direction changing unit that changes the conveyance direction of the polarizing film 3. The steering lever 23 maintains the conveyance direction of the polarizing film 3 of the conveyance mechanism 11 (i.e., the conveyance direction of the polarizing film 3 from the conveyance roller 212 to the winding roller 211) in accordance with the movement of the conveyance mechanism 11 of the movement mechanism 13, and changes the conveyance direction of the polarizing film 3 so as not to generate unnecessary tension on the polarizing film 3.

The steering rod 23 may be provided so as to be able to adjust the extending direction of the steering rod 23 with respect to the feeding direction of the polarizing film 3 fed from the accumulator 22 to the steering rod 23 in accordance with the movement of the feeding mechanism 11 by the moving mechanism 13. The adjustment of the direction in which the steering rod 23 extends may be performed by the analyzer 14, for example. The steering rod 23 may also be part of the inspection device 10.

The number of the steering levers 23 is not limited to one. The number and arrangement of the steering levers 23 can be set so that the polarizing film 3 is not unnecessarily tensioned while maintaining the conveying direction of the polarizing film 3 by the conveying mechanism 21 in the inspection image obtaining step S21.

In the film inspection step S20 of modification 1, as described above, the polarizing film 3 is inspected while the transport mechanism 11 is moved in the first movement direction D3 (more specifically, while the polarizing film 3 is moved) by the movement mechanism 13 in a state in which the inspection optical system 12 is fixed. Therefore, modification 1 also has the same operational advantages as the case of the inspection apparatus 10 and the film inspection method using the same. In modification 1, the polarizing film 3 can be easily inspected for substantially the entire length direction thereof.

(second modification)

When the first angle θ 1 is 15 ° or more and less than 90 ° or more and 165 ° or 45 ° or more and less than 90 ° or more and more than 90 ° and 135 ° or less, the inspection optical system may be moved. A case where the inspection optical system is moved will be described as a second modification. In the second modification, the extending direction D2 is also non-orthogonal to the reference direction D1. The meaning of non-orthogonal is as described above.

The inspection apparatus 30 that performs the film inspection step S20 of the second modification includes the conveyance mechanism 11, the inspection optical system 31, and the movement mechanism 32. The conveyance mechanism 11 is the same as the inspection apparatus 10, and therefore, the explanation of the conveyance mechanism 11 is omitted. A schematic configuration of the inspection optical system 31 and the moving mechanism 32 included in the inspection apparatus 30 will be described with reference to fig. 14. Fig. 14 schematically shows a case where the inspection optical system 31 and the moving mechanism 32 are viewed from a direction orthogonal to the extending direction of the illumination unit 121. In fig. 14, the conveying mechanism 11 is not shown.

As shown in fig. 14, the inspection optical system 31 includes an illumination unit 121, an imaging unit 122, and a coupling unit 311 that integrally couples these components. The configuration of the illumination unit 121 and the imaging unit 122 and the arrangement relationship thereof are the same as those of the inspection apparatus 10. In fig. 14, the illumination section 121 is schematically illustrated. The coupling portion 311 may have a structure that does not interfere with the film 1 when the inspection optical system 31 is moved in the first movement direction D3. For example, when the coupling portion 311 has a U shape as shown in fig. 14, the length of the coupling portion 311 in the first moving direction D3 may be equal to or longer than the length of the film 1 in the first moving direction D3.

The moving mechanism 32 includes: a guide portion 321 extending in the first moving direction D3 of the inspection optical system 31; and a support portion 322 that is attached to the guide portion 321 so as to be movable in the extending direction of the guide portion 321, and supports the connection portion 311. The support portion 322 is electrically movably attached to the guide portion 321 in the first movement direction D3.

When the width of the film 1 is long (in other words, when the moving distance of the inspection optical system 31 in the first moving direction D3 is long), for example, the plurality of inspection optical systems 31 may be moved by the moving mechanism 32. For example, when two inspection optical systems 31 are used, one inspection optical system 31 may be disposed on one edge portion side of the film 1 and the other inspection optical system 31 may be disposed on the other edge portion side in the width direction of the film 1. Accordingly, compared to the case where all the regions are imaged in the first movement direction D3 by one inspection optical system 31, the movement distance of each inspection optical system 31 is shorter, and therefore the length of the coupling portion 311 in the first movement direction D3 can be shortened.

In the second modification, the inspection of the film 1 may be performed by imaging the film 1 while moving the connection portion 311 in the first movement direction D3 along the guide portion 321. The movement state of the connection portion 311 may be controlled by the analysis device 14, for example.

The film inspection step S20 of the second modification includes an inspection image acquisition step S21, a determination step S22, and a range change step S23 shown in fig. 7, similarly to the case where the film inspection step S20 of the inspection apparatus 10 is used. The film inspection step S20 in the second modification is the same as the film inspection step S20 described above, except that the transport mechanism 11 is not moved in the inspection image acquisition step S21, and the inspection optical system 31 is moved relative to the film 1 by the movement mechanism 32. Thus, the defect 5 shown in fig. 3 can be detected. When the inspection optical system 31 is moved, for example, the inspection optical system 31 is moved so that the deviation in the positional relationship between the imaging unit 122 and the illumination unit 121 is equal to or less than the resolution of the imaging unit 122. As shown in fig. 14, when the illumination unit 121 and the imaging unit 122 of the inspection optical system 31 are coupled by the coupling unit 311, the positional relationship between the imaging unit 122 and the illumination unit 121 is not likely to be deviated, and the inspection optical system 31 is likely to be moved so that the deviation of the positional relationship is equal to or smaller than the resolution of the imaging unit 122.

In the second modification, a case where the inspection optical system 31 is moved relative to the film 1 without moving the conveyance mechanism 11 is mainly described. However, the inspection apparatus 30 may further include the moving mechanism 13 shown in fig. 4, and the conveying mechanism 11 (specifically, the film 1) may be moved by the moving mechanism 13 together with the inspection optical system 31. That is, when the first angle θ 1 is 15 ° or more and less than 90 ° or more and 165 ° or 45 ° or more and less than 90 ° or more and 90 ° and 135 ° or less, the other one may be moved in the first moving direction D3 with respect to one of the inspection optical system 31 and the film 1 (or the conveying mechanism 11).

(third modification)

In fig. 4, when the region of the film 1 between the conveying

rollers

112 and 113 is set as the entire inspection range of the film, for example, in the inspection range changing step S22, the conveying mechanism 11 itself (i.e., the film 1) may be further moved in the second moving direction (third direction) D4 different from the first moving direction D3.

Fig. 15 is a diagram for explaining the relationship among the reference direction D1, the extending direction D2 of the imaging area a, the first moving direction D3, and the second moving direction D4. The relationship of the first angle θ 1 between the reference direction D1 and the first moving direction D3 and the second angle θ 2 between the first moving direction D3 and the extending direction D2 is the same as the case of fig. 6. Further, in the third modification, the extending direction D2 is not orthogonal to the reference direction D1. In the third modification, the angle formed by the extending direction D2 and the reference direction D1 may be different from 75 ° to 105 °, for example. The second moving direction D4 is different from the first moving direction D3, and a third angle θ 3 between the first moving direction D3 and the second moving direction D4 is 15 ° to 165 ° or 45 ° to 135 °. The second moving direction D4 may be the same as the extending direction D2 of the photographing region a.

As shown in fig. 16, an inspection apparatus 40 for performing a film inspection process S20 according to a third modification for moving a film 1 in a first moving direction D3 and a second moving direction D4 includes a transport mechanism 11, an inspection optical system 12, and a moving mechanism 41. The conveyance mechanism 11 and the inspection optical system 12 are the same as those of the inspection apparatus 10, and therefore, description thereof is omitted.

The moving mechanism 41 is a 2-axis table that can move the film 1 in the first moving direction D3 and can move in the second moving direction D4. For example, the moving mechanism 41 includes a first moving mechanism 411 that moves the film 1 in the first moving direction D3 and a second moving mechanism 412 that moves the film 1 in the second moving direction D4. The structure of the first moving mechanism 411 can be the same as the moving mechanism 13 of fig. 4. The second moving mechanism 412 is disposed on the first moving mechanism 411, and the conveying mechanism 11 is fixed to the second moving mechanism 412. The second movement mechanism 412 can be configured in the same manner as the first movement mechanism 411, that is, the movement mechanism 13 in fig. 4, except that the extending direction of the guide portion is the second movement direction D4. For example, the second moving mechanism 412 may include a base plate, a moving stage, and a guide portion provided therebetween and extending in the second moving direction D4, and the moving stage may be configured to be movable in the second moving direction D4 along the guide portion with respect to the base plate. When the second moving mechanism 412 includes the base plate and the mobile station as described above, the base plate on the second moving mechanism 412 side may be shared with the mobile station of the first moving mechanism 411.

The movement of the film 1 in the second movement direction D4 by the movement mechanism 41 includes a case where the film 1 is moved in a second forward direction of the second movement direction D4 and a case where the film 1 is moved in a second reverse direction opposite to the second forward direction in the second movement direction D4.

In the third modification, by repeating the inspection image obtaining step S21 and the range changing step S23, the region of the film 1 between the conveying

rollers

112 and 113 in the film 1 can be inspected as the entire inspection range. After the inspection of the inspection range is completed, the film 1 may be conveyed in the conveying direction by the conveying mechanism 11, for example, and the range of the film 1 may be further inspected.

(fourth modification)

The inspection optical system 12 is not limited to the transmission optical system, and may be a reflection optical system. That is, the illumination unit 121 and the imaging unit 122 may be disposed on the same side of the film 1. Further, the inspection optical system 12 may be a combination of a transmission optical system and a reflection optical system. In this case, the inspection optical system 12 may have: an imaging unit 122; a first illumination unit disposed on the opposite side of the film 1 from the imaging unit 122 and forming a transmission optical system; and a second illumination unit disposed on the same side of the film 1 as the imaging unit 122 and forming a reflection optical system. As illustrated in fig. 4, the first illumination unit and the second illumination unit may include a light source 121a and a light shielding body 121 b.

Various modifications have been described above together with the embodiments. However, the present invention is not limited to the above-described embodiments and various modifications, and includes the scope indicated by the claims, and all modifications within the meaning and scope equivalent to the claims.

Therefore, for example, the above embodiments may be combined as appropriate in various modifications within a scope not departing from the gist of the present invention. For example, the first modification may be applied to the second to fourth modifications, and the polarizing film 3 formed in the film forming step S10 of fig. 1 may be inspected before the polarizing film 3 is wound around a winding roll. The third modification may be applied to the first modification and the fourth modification, and the inspection range may be changed by moving the inspection object (the film 1 or the polarizing film 3) in the second moving direction D4 in the range changing step S23 in fig. 7. The third modification can also be applied to the second modification. In this case, in the range changing step S23 in fig. 7, the inspection range may be changed by moving one of the film 1 and the inspection optical system 31 relative to the other in the second moving direction D4. In the first to third modifications, the fourth modification may be applied, and a reflection optical system may be used as the inspection optical system, or an optical system combining a transmission optical system and a reflection optical system may be used.

When the inspection image obtaining step S21 of fig. 7 can be performed once to inspect the entire desired inspection range of the inspection object, it is not necessary to perform the other steps of fig. 7 (the determination step S22 and the range changing step S23).

In the embodiment in which the inspection optical system is a scattering optical system, the illumination unit may not have a light shielding body. For example, the imaging unit may be configured to realize a scattering optical system by arranging the illumination unit and the imaging unit so that an area illuminated by light scattered at an end of the illumination unit is imaged. The inspection optical system is not limited to a scattering optical system.

As described above, since the defect 5 is often formed by extending the damage generated before the extension process such as the extension process, the inspection method and the inspection apparatus described in the above embodiment and various modifications are effective for inspecting the defect 5 of the extended film. However, for example, when the film is conveyed by the conveying rollers, since tension is applied in the conveying direction of the film, the defect 5 may be generated as in the case of the stretching process. Therefore, the present invention is also effective for defect inspection of a long film when the film is formed in a roll-to-roll manner, for example.

In the inspection apparatus and the inspection method described in the above embodiments and various modifications, if the reference direction, the moving direction (first direction) of at least one of the film and the optical system, and the extending direction (second direction) of the imaging region satisfy the above-described relationship, a defect extending substantially in the reference direction (that is, a defect extending in one direction that satisfies a certain relationship with respect to the first direction and the second direction) can be detected. Therefore, the reference direction of the film is not limited to the longitudinal direction of the film conveyed by the conveying roller or the conveying direction of the film. When the direction of extension of a defect to be detected in the film is assumed in advance, the assumed direction of extension of the defect may be set as the reference direction of the film. An arbitrary direction may be set as a reference direction in the film. In this case, in the case where a defect extending in the reference direction is generated, the defect can be detected.

In the above description, the case where there is only one inspection optical system has been mainly described. However, the inspection optical system as a set of the illumination unit and the imaging unit may be provided in two or more numbers with respect to the film. In this case, considering the inspection range by the plurality of inspection optical systems, in the inspection image acquisition step, when the first angle θ 1 includes 90 °, the film may be moved relative to the inspection optical system, and when the first angle θ 1 does not include 90 °, one of the film and the inspection optical system may be moved relative to the other.

In the description so far, the film formed in the film forming step is a part of the polarizing film, and the polarizing film (or a film cut out from the polarizing film) is an inspection object. However, the film of the inspection object is not limited to the polarizing film. For example, the polarizing film may be a laminated film in which another film (e.g., a protective film or a retardation film) is further laminated, or may be a separator of a battery. The film to be inspected is not limited to a long film, and may be a single film.

Description of the symbols

1 … film, 10, 20, 30, 40 … inspection device, 11, 21 … conveying mechanism, 12, 31 … inspection optical system, 13, 32, 41 … moving mechanism, 121 … illuminating part, 122 … imaging part, a … imaging area, D1 … reference direction, D2 … extending direction (second direction), D3 … first moving direction (first direction), and D4 … second moving direction (third direction).

Claims

1. An inspection device is provided with:

an inspection optical system including an illumination unit configured to illuminate a film, and an imaging unit configured to receive light from the film illuminated by the illumination unit and acquire an inspection image for defect determination; and

a moving mechanism which moves the film,

the inspection optical system is fixedly arranged independently of the moving mechanism,

the moving mechanism has a mechanism for moving the film in a first direction different from a reference direction of the film with respect to the inspection optical system,

a photographing region of the inspection optical system extends in a second direction different from the first direction,

the reference direction, the first direction, and the second direction are orthogonal to a thickness direction of the film,

a first angle between the reference direction and the first direction is 15 DEG or more and 165 DEG or less,

a second angle between the first direction and the second direction is 15 DEG or more and 165 DEG or less,

the reference direction is non-orthogonal to the second direction.

2. The inspection apparatus according to claim 1,

the inspection optical system is a scattering optical system.

3. The inspection apparatus according to claim 1 or 2,

the moving mechanism further has a mechanism that moves the film relative to the inspection optical system in a third direction that is different from the first direction and orthogonal to the thickness direction,

a third angle between the first direction and the third direction is 15 ° or more and 165 ° or less.

4. An inspection device is provided with:

a moving mechanism that moves the film or the inspection optical system,

the moving mechanism includes a mechanism for moving one of the film and the inspection optical system relative to the other in a first direction different from a reference direction of the film,

a photographing region of the inspection optical system extends to a second direction different from the first direction,

a first angle between the reference direction and the first direction is 15 ° or more and less than 90 ° or more than 90 ° and 165 ° or less,

the reference direction is non-orthogonal to the second direction.

5. The inspection apparatus according to claim 4,

the moving mechanism further includes a mechanism for moving one of the film and the inspection optical system relative to the other in a third direction different from the first direction and orthogonal to the thickness direction,

6. The inspection apparatus according to any one of claims 1 to 5,

the inspection apparatus includes a conveying mechanism for conveying the film in the reference direction,

the moving mechanism moves the film by moving the conveying mechanism.

7. The inspection apparatus according to any one of claims 1 to 6,

the film is a long strip of film,

the reference direction is a longitudinal direction of the film.

8. The inspection apparatus according to any one of claims 1 to 7,

the film comprises an extended film extending in one direction,

the reference direction is an extending direction of the extended film.

9. An inspection method for inspecting a film by acquiring an inspection image of the film in order to determine a defect,

the inspection method includes an inspection image acquisition step of acquiring an inspection image for defect determination by imaging the film by an imaging unit of an inspection optical system while illuminating the film by an illumination unit of the inspection optical system,

in the inspection image acquisition step, the inspection image is acquired while moving the film relative to the inspection optical system in a first direction different from a reference direction of the film,

the reference direction is non-orthogonal to the second direction.

10. The inspection method according to claim 9,

the inspection optical system is a scattering optical system.

11. An inspection method for inspecting a film by acquiring an inspection image of the film in order to determine a defect,

in the inspection image obtaining step, an inspection image is obtained while moving one of the film and the inspection optical system relative to the other in a first direction different from a reference direction of the film,

the reference direction is non-orthogonal to the second direction.

12. The inspection method according to any one of claims 9 to 11,

a range changing step of changing an inspection range of the film based on the inspection image acquiring step,

alternately performing an inspection image acquisition step and the range changing step until the inspection image of all inspection ranges preset in the film is acquired.

13. The inspection method according to claim 12,

in the range changing step, the inspection range is changed by moving the film in a third direction that is different from the first direction and orthogonal to the thickness direction.

14. The inspection method according to claim 12,

in the range changing step, the inspection range is changed by conveying the film in the reference direction.

15. The inspection method according to any one of claims 9 to 14,

the film is a long strip of film,

the reference direction is a longitudinal direction of the film.

16. The inspection method according to any one of claims 9 to 15,

the film includes an extended film extending in one direction,

the reference direction is an extending direction of the extended film.

17. A method for producing a film, comprising a step of coating a film,

the method for producing a film has a step of inspecting the film by the inspection method according to any one of claims 9 to 16.