Inspection device

Abstract

The utility model provides a kind of inspection device of checking whether there is defect in circular polarizing plate, its structure is relatively simple and can reduce the omission of defect.The inspection device (1) has: polarizing filter (17), light source (13) being arranged in one side of polarizing filter (17), rotation component (11) can make polarizing filter rotate in its in-plane direction with the direction of polarizing filter (17) and light source (13) arrangement as axis direction, sliding support mechanism (20) being arranged in the other side of polarizing filter (17) and supporting the sliding of the object (2) in the direction being substantially orthogonal with axis direction along its in-plane direction when checking, and the component (30) of making parallel light being arranged between polarizing filter (17) and sliding support mechanism (20) and removing diffuse light from the light emitted by light source (13) and passed through polarizing filter (17).If the object (2) is slid while checking, in the case that there is optical defect in circular polarizing plate, the defect looks like being emphasized as residual image.

Description

Technical Field

[0001] This utility model relates to an inspection device. Background Technology

[0002] Conventional inspection devices have been proposed for checking whether a circular polarizing plate has defects. For example, taking one embodiment of the inspection device disclosed in Patent Document 1 as an example, light is shone onto the circular polarizing plate to be inspected, causing the transmitted light to be reflected back to the polarizing plate by a reflecting member. In this case, in the normal portion of the circular polarizing plate, the light reflected by the reflecting member cannot pass through the plate. However, if the circular polarizing plate has a defect, the polarization state is disturbed in the defective portion, and therefore the light reflected by the reflecting member contains a component that has passed through the circular polarizing plate. Therefore, when the circular polarizing plate has a defect, the defect is observed as a bright spot in a black field of view.

[0003] While this inspection device can perform general defect detection, it is prone to missing defects with phase differences on the order of a few nanometers. However, if an imaging device or a resolution device is used to compensate for this, the inspection device becomes large-scale. Here, in the inspection device disclosed in Patent Document 2, although the structure is relatively simple, the detection accuracy of defects is successfully improved by rotating the polarizing filter so that the direction of the optical axis of the polarizing filter is aligned with the direction suitable for inspection.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-53057

[0007] Patent Document 2: Japanese Utility Model Registration No. 3228809 Utility Model Content

[0008] The problem to be solved by utility models

[0009] However, in the inspection device of Patent Document 2, there is a situation where defects are difficult to visually identify due to the influence of diffused light contained in the inspection light. Therefore, the purpose of this invention is to provide an inspection device for detecting defects with higher precision.

[0010] Methods for solving problems

[0011] This invention provides an inspection device for inspecting a film-like object containing a circular polarizing plate for defects. The inspection device comprises: a polarizing filter; a light source disposed on one side of the polarizing filter; a rotating member capable of rotating the polarizing filter in its in-plane direction about the axis in which the polarizing filter and the light source are aligned; a sliding support mechanism disposed on the other side of the polarizing filter, supporting the object to slide in its in-plane direction in a direction approximately orthogonal to the axis during inspection; and a member for generating parallel light, disposed between the polarizing filter and the sliding support mechanism, removing diffused light from the light emitted from the light source and transmitted through the polarizing filter.

[0012] When inspecting a circular polarizer for defects using this inspection device, the polarizing filter is rotated using a rotating member, aligning the optical axis of the polarizing filter with the direction suitable for inspection. The object to be inspected is then slid along the filter while being supported by a sliding support mechanism. In the event of an optical defect in the circular polarizer, this defect appears as a residual image during the sliding process. Even if the defect is only a phase difference on the order of a few nanometers, this emphasized residual image can be clearly discerned with the naked eye, thus reducing the chance of defects being missed even without a special inspection device. Furthermore, the light emitted from the light source is de-spread by a member that creates parallel light, allowing the light from the light source to be incident on the object from the front, thereby improving the accuracy of the inspection.

[0013] Preferably, the inspection device further includes a phase difference compensation plate between the component that generates parallel light and the sliding support mechanism to compensate for the phase difference in the thickness direction. When the object being inspected has a release film made of polyethylene terephthalate resin, which has a phase difference in the thickness direction, and this phase difference occurs in the field of view for some reason, if the inspection device includes a phase difference compensation plate, it can compensate for the phase difference in the tilt direction within the field of view, enabling accurate observation over a wider range.

[0014] Preferably, the inspection device also includes a condenser lens between the component that generates parallel light and the phase difference compensation plate. If the inspection device includes a condenser lens at this location, it can suppress light diffusion that has passed through the component that generates parallel light.

[0015] Preferably, the inspection device also includes a reflective polarizer between the polarizing filter and the light source. This improves the utilization efficiency of the light emitted by the light source.

[0016] In this inspection apparatus, the component for generating parallel light has: an internal space through which light emitted from a light source passes toward the object being inspected; and a through hole that connects the internal space to the outside of the component for generating parallel light, guiding light emitted from the light source that is not directed toward the object being inspected outward. This makes the removal of diffused light highly efficient, enabling more aligned parallel light to be directed toward the object being inspected.

[0017] Preferably, the sliding support mechanism includes: a stage arranged such that its mounting surface is substantially parallel to the surface of the polarizing filter; and a guide arranged extending in one direction on the mounting surface. The stage is provided with a window that allows light emitted from a light source and transmitted through the polarizing filter to pass through. With this stage and guide, the object to be inspected can be easily slid in one direction.

[0018] Preferably, the sliding support mechanism also includes a movable plate, the thick portion of which can abut against the guide, and the movable plate can slide on the mounting surface along the extending direction of the guide. The movable plate is provided with a window that allows light emitted from a light source, passing through a polarizing filter and through the window of the mounting stage to pass through. With this movable plate, the object to be inspected can be easily slid along the guide.

[0019] Preferably, when the object to be inspected has a release film with a phase difference that is attached to the circular polarizer, the polarizing filter is configured to have two regions with different optical axis directions when viewed from above. This allows for the following inspection steps: before inspection, the rotating member is operated to find an angle that can eliminate the phase difference of the release film by utilizing the relationship between the optical axis of one region of the polarizing filter and the optical axis of the release film, thus fixing the angle of the polarizing filter; during inspection, the other region of the polarizing filter is used for inspection while maintaining this angle.

[0020] Circular polarizers can have a retardation film formed from polymeric liquid crystal compounds. The retardation film formed from polymeric liquid crystal compounds is typically thinner than retardation films formed by other methods. Even with such a thin retardation film, the color unevenness defects caused by phase difference variations of a few nanometers can be reduced by the inspection device of this invention.

[0021] Utility Model Effect

[0022] According to this utility model, an inspection device with a relatively simple structure and the ability to reduce the omission of defects can be provided. Attached Figure Description

[0023] Figure 1 This is a top view of an inspection device according to one embodiment of the present invention.

[0024] Figure 2 It is along Figure 1 A side sectional view of line II-II.

[0025] Figure 3 This is a top view of a polarizing filter.

[0026] Figure 4 It is a top view showing the relationship between the components that produce parallel light and the lens.

[0027] Figure 5 Both (A) and (B) are diagrams illustrating the structure of components used to create parallel light.

[0028] Figure 6 This is a partial side view showing the structure of the phase difference compensation plate.

[0029] Figure 7 This is a top view of the inspection device when adjusting the rotation angle of the polarizing filter.

[0030] Figure 8 (A), (B), and (C) are all top views showing the situation where the angle of the polarizing filter changes.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1…Inspection device, 2…Object to be inspected, 3…Stage, 4…Support, 10…Rotating mechanism, 11…Rotating component, 11a…Lower component, 11b…Upper component, 13…Light source, 15…Reflective polarizer, 17…Polarizing filter, 17a…First region, 17b…Second region, 19…Operating rod, 20…Sliding support mechanism, 21…Stage, 21a…Window of stage, 23A…Sliding guide, 23B…Rotation angle adjustment Using guides, 25… movable plate, 25a… window of movable plate, 27A, 27B… positioning components, 29… glass plate, 30… component for making parallel light, 31… through hole, 32… plastic corrugated plate, 33… through hole, 34… internal space, 40… condenser lens, 50… phase difference compensation plate, 51… basic stack, 52… additional stack, P1… optical axis of the first region, P2… optical axis of the second region, R… field of view, S… axis. Detailed Implementation

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the various figures, the same or equivalent parts are labeled with the same reference numerals, and repeated descriptions are omitted. In this embodiment, the case where the inspection device is placed on a horizontal platform will be described. That is, the axis of rotation of the rotating member described later is oriented in the vertical direction, and the direction in which the object being inspected slides during inspection is horizontal. It should be noted that in this specification, "sliding" refers to moving the position of a member relative to other members whose positions are fixed, whether these members are in direct contact or not.

[0034] (Item being inspected)

[0035] The object under inspection is an optical film equipped with a circular polarizer. A circular polarizer is formed by forming a phase retardation film on a polarizer to which a protective film is laminated on one or both sides. This phase retardation film can be a film that exhibits phase retardation by extending a resin film, or it can be formed by coating a polymeric liquid crystal compound onto the polarizer and then drying it. It should be noted that in this specification, "circular polarizer" includes both circular polarizers (λ / 4 plates) and elliptical polarizers.

[0036] The component consisting solely of the circular polarizer can be used as the object to be inspected, but various other films can also be laminated onto the circular polarizer. For example, an adhesive layer and a release film can be laminated on the phase retardation film side. This release film is the film that is peeled off when the circular polarizer is attached to the image display device via its adhesive layer. The material of the release film can be polyethylene terephthalate. Alternatively, a surface protective film for protecting its surface can be laminated on the polarizer side. Even when the release film and surface protective film have a phase retardation, as described later, the inspection apparatus according to this embodiment can inspect the circular polarizer for defects without causing any obstruction.

[0037] (Inspection device)

[0038] like Figure 1 and Figure 2 As shown, the inspection device 1 of this embodiment includes: a rotating mechanism 10, which is located at the lower part of the inspection device 1 when it is placed on a horizontal platform; and a sliding support mechanism 20, which is disposed above the rotating mechanism 10. A component 30 for producing parallel light, a condenser lens 40, and a phase difference compensation plate 50 are also provided sequentially from the rotating mechanism 10 side between the rotating mechanism 10 and the sliding support mechanism 20.

[0039] Rotating mechanism 10 is used for inspecting the object 2 (see reference) which is the object of inspection. Figure 2 The mechanism for incident light suitable for inspection is composed of a rotating component 11, a light source 13, a reflective polarizer 15, and a film-shaped polarizing filter 17 stacked in sequence.

[0040] The rotating member 11 can be any member capable of rotating about a predetermined axis S facing the vertical direction, such as a bearing housing. The rotating member 11 is placed on a horizontal platform 3. In the case where the rotating member 11 is a bearing housing, its lower member 11a is fixed to the platform 3, and its upper member 11b rotates. One end of the operating rod 19 extending in the horizontal direction is fixed and mounted to the upper member 11b, and the other end of the operating rod 19 extends to a length that extends outward beyond the platform 21 when the entire inspection device 1 is viewed from above (see reference). Figure 1 By moving the operating rod 19 in the horizontal direction, the upper component 11b rotates.

[0041] A light source 13 is mounted on the rotating member 11, emitting light vertically upwards. The light source 13 can be any commercially available product that emits unpolarized light. It should be noted that... Figure 2 In the diagram, the width of the light source 13 is depicted as wider than the width of the polarizing filter 17, but the range of light emission in the light source 13 is narrower than the width of the polarizing filter 17.

[0042] A reflective polarizer 15 is mounted on the light source 13. The reflective polarizer 15 reflects the light emitted from the light source 13 that has not passed through the polarizing filter 17 (described later), and directs it back toward the polarizing filter 17.

[0043] A polarizing filter 17 is mounted on a reflective polarizer 15. The polarizing filter 17 is a rectangular linear polarizer. The polarizing filter 17 receives light that has passed through the reflective polarizer 15 and converts unpolarized light into linearly polarized light. Figure 3 As shown, the polarizing filter 17, when viewed from above, has a first region 17a and a second region 17b with opposite optical axis (absorption axis or transmission axis) orientations. The polarizing filter 17 is linearly divided such that, when viewed from above, the areas of the first region 17a and the second region 17b are, for example, 3:1, and the optical axis P1 of the first region and the optical axis P2 of the second region 17b are orthogonal to each other. Taking one side of the polarizing filter 17 as a reference, for example, the optical axis P1 of the first region 17a is 135°, and the optical axis P2 of the second region 17b is 45°. As will be described later, during inspection, the narrower second region 17b is used to adjust the rotation angle of the polarizing filter 17, while the larger first region 17a is used for inspection. Such a polarizing filter 17 can be manufactured as follows: polarizing filters prepared by cutting portions constituting the first region 17a and the second region 17b from other polarizing plates, respectively, are bonded together at their thicknesses, taking into account that their optical axis orientations are as described above.

[0044] The sliding support mechanism 20 is a mechanism for supporting the inspection object 2, which is the object to be inspected, to be placed during inspection and for allowing the inspection object 2 to slide in the horizontal direction. It includes: a platform 21; a sliding guide 23A, which is arranged on the platform in a manner that extends in one direction; a movable plate 25, which is placed on the platform 21; and a glass plate 29, which is placed on the movable plate 25.

[0045] The stage 21 is a plate-shaped member having an upper surface parallel to the plane of the polarizing filter 17 (i.e., horizontal in this embodiment). It is supported on the platform 3 by the supports 4, 4, and is arranged to cover the entire structure of the rotating mechanism 10 described above. The stage 21 is made of a material that prevents light emitted from the light source 13 from passing through. From the viewpoint of reducing the diffusion of the produced parallel light, the distance between the lower surface of the stage 21 and the member 30 for producing parallel light is preferably 50 mm or less.

[0046] The mounting platform 21 is rectangular when viewed from above, and a rectangular window 21a is provided at approximately its center. The window 21a exists as a hole that passes through the mounting platform 21 in the thickness direction. The long and short sides of the rectangle of the window 21a are respectively oriented parallel to the long and short sides of the rectangle of the mounting platform 21.

[0047] A sliding guide 23A is disposed on the mounting surface of the mounting stage 21. The sliding guide 23A is a rod-shaped section rectangle and is fixed at a position biased towards one of the long sides of the mounting stage 21, extending in the direction of its long side. Additionally, a rotation angle adjustment guide 23B is disposed on the mounting surface of the mounting stage 21. The rotation angle adjustment guide 23B is a rod-shaped section rectangle and is fixed at a position biased towards the short side of the mounting stage 21, extending in the direction of its short side and forming a 90° angle with the sliding guide.

[0048] A movable plate 25 is mounted on the mounting surface of the mounting platform 21. The movable plate 25 is a rectangular plate-shaped member, the size of which is larger than the rectangular window portion 21a provided on the mounting platform 21. The movable plate 25 is made of a material that prevents light emitted from the light source 13 from passing through. The movable plate 25 is arranged such that the long and short sides of its rectangle are parallel to the long and short sides of the rectangle of the mounting platform 21, respectively. Therefore, the thick portion of the long side of the movable plate 25 can abut against the sliding guide 23A (see reference). Figure 1 and Figure 2 Furthermore, the thick portion of the short side of the movable plate 25 can abut against the rotation angle adjustment guide 23B (see reference). Figure 7 The movable plate 25 can slide in either the extension direction of the sliding guide 23A or the extension direction of the rotation angle adjustment guide 23B.

[0049] Furthermore, a rectangular window 25a is provided approximately at the center of the movable plate 25 when viewed from above. The window 25a serves as a hole penetrating the movable plate 25 in the thickness direction. The long and short sides of the rectangle of the window 25a of the movable plate 25 are respectively oriented parallel to the long and short sides of the rectangle of the movable plate 25. The size of the window 25a of the movable plate 25 is smaller than the size of the window 21a of the stage 21, but when the movable plate 25 abuts against the sliding guide 23A or the rotation angle adjustment guide 23B, it also has the degree to which the window 25a overlaps with the window 21a of the stage 21 when viewed from above, allowing observation of the polarizing filter 17 (see reference). Figure 1 and Figure 7 ).

[0050] On the mounting surface of the movable plate 25, two positioning members 27A and 27B are arranged near the edge of the window portion 25a. Both positioning members 27A and 27B are rectangular rods in cross-section. The length of one positioning member 27A is shorter than the length of the long side of the window portion 25a, and the length of the other positioning member 27B is shorter than the length of the short side of the window portion 25a. They are fixed along the edges of the long and short sides of the window portion 25a, respectively. Therefore, the two positioning members 27A and 27B are fixed in an orthogonal orientation.

[0051] A glass plate 29 is placed on the mounting surface of the movable plate 25. The glass plate 29, when viewed from above, is rectangular in size, large enough to completely cover the window portion 25a, and is positioned such that its adjacent sides abut against positioning members 27A and 27B, respectively. During inspection, the object to be inspected 2 is placed on the glass plate 29. Figure 2 In the middle, the object 2 being inspected is depicted with imaginary lines. Although it depends on the size of the object 2 being inspected, by having a glass plate 29, it is possible to prevent the object 2 being inspected from falling from the window 25a or to prevent the object 2 being inspected from bending toward the window 25a.

[0052] The component 30 for creating parallel light is a component that removes diffused light from the light emitted from the light source 13 and allows parallel light to pass through. For example... Figure 2 and Figure 4 As shown, the component 30 for generating parallel light is a rectangular parallelepiped mounted on the polarizing filter 17, and has a roughly square through-hole 31 in the center when viewed from above. That is, the component 30 for generating parallel light is annular around an internal space 34 extending vertically. The lower part of the internal space 34 is closed by the contact between the component 30 for generating parallel light and the polarizing filter 17, and the upper part of the internal space 34 is covered by a condensing lens 40, which will be described later.

[0053] like Figure 5 As shown, the component 30 for creating parallel light is formed by stacking multiple rectangular plastic corrugated sheets 32 when viewed from above. Figure 5(A) is a side view of a plastic corrugated sheet 32. Figure 5 (B) is a perspective view showing a case where multiple plastic corrugated sheets 32 are stacked. The plastic corrugated sheets 32 have, for example, a thickness of 4 mm to 12 mm in the thickness portion of the plastic sheet with a shape along one direction (…). Figure 5 Multiple through holes 33 extending in the depth direction of (A). Each through hole 33 has a square opening shape, and each through hole 33 extends in other directions perpendicular to the aforementioned direction (…). Figure 5 The diagram of (A) is arranged neatly in the left-right direction. The square with the opening shape is, for example, 5mm to 10mm square.

[0054] The component 30 for creating parallel light is constructed by stacking multiple plastic corrugated sheets 32 in a manner where each sheet extends in a different direction from the others through holes 33. Each through hole 33, opening into the internal space 34 of the component 30, serves as a horizontal passage connecting the internal space 34 to the outside. It should be noted that during the fabrication of the component 30, the internal space 34 can be created by excavating after stacking the plastic corrugated sheets 32, or it can be stacked after each plastic corrugated sheet 32 ​​has been pre-set as a window within the internal space 34.

[0055] The height of the component 30 for creating parallel light can be 10cm to 20cm, or 12cm to 18cm. When the plastic corrugated sheet 32 ​​is black, it also has the effect of absorbing and removing non-parallel light, and is therefore preferred.

[0056] The condenser lens 40 is a convex lens, a component used to focus light so that it reliably reaches the object 2 being inspected after passing through the internal space 34 of the component that creates parallel light 30. For example... Figure 2 and Figure 4 As shown, the condenser lens 40 is placed on the upper surface of the component 30 for producing parallel light, and has a size that can completely cover the opening portion of the internal space 34 of the component 30 for producing parallel light when viewed from above.

[0057] Phase difference compensation plate 50 is used to compensate for the phase difference R in the thickness direction that occurs within the field of view due to some reason. th The compensation plate. The phase difference compensation plate 50, viewed from above, is rectangular and composed of multiple stacked C-plates. Specifically, as... Figure 6As shown, the phase difference compensation plate 50 is formed by stacking 0 to 5 additional stacks 52, each consisting of 5 positive C plates, on top of a basic stack 51, which consists of 80 positive C plates. The phase difference compensation plate 50 has at its ends portions consisting only of the basic stack 51 without additional stacks 52, portions with one additional stack 52, portions with two additional stacks 52, portions with three additional stacks 52, portions with four additional stacks 52, and portions with five additional stacks 52, these portions increasing in a stepped manner. Thus, the phase difference compensation plate 50 has portions with 80 positive C plates, portions with 85 positive C plates, portions with 90 positive C plates, portions with 95 positive C plates, portions with 100 positive C plates, and portions with 105 positive C plates.

[0058] The phase difference compensation plate 50 is slidably mounted on the back of the stage 21. During inspection, the phase difference compensation plate 50 can be slid in the in-plane direction as needed, allowing the number of positive C-plates of the phase difference compensation plate 50 within the aforementioned range of 85 to 105 sheets to be varied. For example, the phase difference R of each positive C-plate can be adjusted. th In the case of -100nm, it can compensate for the phase difference of -8500nm to -10500nm.

[0059] In the inspection apparatus 1 configured as described above, the light emitted from the light source 13 passes sequentially through a reflective polarizer 15, a polarizing filter 17, the internal space 34 of the component 30 for producing parallel light, a condenser lens 40, a phase difference compensation plate 50, a window 21a of the stage 21, a window 25a of the movable plate 25, and a glass plate 29 before reaching the object to be inspected 2. Figure 2 It can also be seen that these components are arranged on the axis S of the rotating component 11.

[0060] (Inspection steps)

[0061] The inspection device 1, configured as described above, is used to inspect the object 2 equipped with a circular polarizing plate. The inspection device 1 is configured to become... Figure 1 The orientation shown is such that, when viewed from the inspector directly opposite the bottom side of the diagram, the sliding guide 23A is positioned to the left and the rotation angle adjustment guide 23B is positioned to the bottom.

[0062] First, place the object to be inspected 2, which is smaller than the window portion 25a of the movable plate 25, on the glass plate 29. If the object to be inspected 2 has a release liner, place it with the release liner facing downwards (towards the glass plate 29). At this time, to prevent the observation field from darkening, pay attention to the orientation of the object to be inspected so that the object to be inspected and the polarizing filter 17 are not in cross-cutting positions. Place the object to be inspected 2 and the glass plate 29 together against the positioning members 27A and 27B. This contact with the positioning members 27A and 27B is maintained in the same position until the inspection is completed, so adhesive tape or the like can be used to fix the position as needed.

[0063] Next, as Figure 7 As shown, the movable plate 25 abuts against the rotation angle adjustment guide 23B. It should be noted that... Figure 7 The description of the object 2 being inspected is omitted. Since the window 21a of the stage 21 and the window 25a of the movable plate 25 overlap when viewed from above, the light emitted from the light source 13, passing through the polarizing filter 17, the internal space 34 of the component 30 that produces parallel light, etc., sequentially passes through the window 21a of the stage 21, the window 25a of the movable plate 25, the glass plate 29, and the object 2 being inspected, and is seen by the inspected person. That is, when viewed from directly above the inspection device 1, the polarizing filter 17 can be seen through the object 2 being inspected. Thus, when observing the polarizing filter 17, the movable plate 25 is slid along with the rotation angle adjustment guide 23B to position the second region 17b of the polarizing filter 17 in a visible position. In this embodiment, the polarizing filter 17 is... Figure 3 The orientation shown applies to the inspection device 1, therefore when the movable plate 25 is oriented... Figure 7 When you move the diagram to the right, the second region 17b becomes easier to see. It should be noted that at this time, as... Figure 8 As shown in (A), the first region 17a can also be seen simultaneously within the field of view R. It should be noted that the size and shape of the field of view R are the size and shape of the window portion 25a itself.

[0064] While observing the polarizing filter 17 through the object 2 under inspection from directly above the inspection device 1, the operation rod 19 is used to rotate the polarizing filter 17 in its in-plane direction. An attempt is made to rotate it to the left (…). Figure 8 (B) and right rotation ( Figure 8 Observe the color of the second region 17b from various angles on both sides (C). Instead of finding the angle at which the second region 17b appears to be colored green or red, find the angle at which it becomes the intermediate color between them, and fix the operating rod 19 at that angle.

[0065] Next, the movable plate 25 is brought into contact with the sliding guide 23A. Figure 1(In the state shown). Since the movable plate 25 is close to the left side of the diagram, when observing the polarizing filter 17 from directly above the inspection device 1 through the object under inspection 2, only the first region 17a is visible. In this state, the movable plate 25 is slid up and down in the direction shown in the diagram while abutting against the sliding guide 23A, and inspection is performed. The sliding of the object under inspection 2 in the in-plane direction is in the form of a reciprocating motion, preferably with a stroke of about 30 mm and a sliding speed of 3 reciprocations per second. By sliding the movable plate 25 relative to the polarizing filter 17, the object under inspection 2 also slides relative to the polarizing filter 17. In this way, the object under inspection 2 is observed while it is sliding.

[0066] During inspection, the phase difference compensation plate 50 can be slid in the in-plane direction as needed, so that portions with different numbers of additional stacked parts 52 are located within the field of view, thereby changing the magnitude of the phase difference compensated by the phase difference compensation plate 50.

[0067] Based on the above inspection steps, it is possible to inspect whether the circular polarizer has color unevenness defects. That is, according to the inspection apparatus 1 of this embodiment, supported by the stage 21, the sliding guide 23A, and the movable plate 25, the object to be inspected 2 can be accurately slid back and forth in one direction. Here, if the circular polarizer of the object to be inspected 2 has optical defects, the defects appear to be emphasized as residual images during the sliding process. Even if the defect is a phase difference on the order of a few nanometers, the emphasized residual image can be fully discerned with the naked eye. Therefore, even without using a complex inspection device, the omission of color unevenness defects can be reduced.

[0068] In the inspection apparatus 1 of this embodiment, when the light emitted by the light source 13 passes through the component 30 that produces parallel light, the light emitted by the light source 13 that is not directed toward the object to be inspected, i.e., diffuse light, enters the through hole 33 and is removed to the outside. As a result, the parallel light is efficiently extracted upwards from the component 30 that produces parallel light. Therefore, parallel light with further reduced diffuse light can be incident on the object to be inspected from the front, thereby improving the accuracy of the inspection.

[0069] Furthermore, the inspection device 1 of this embodiment includes a phase difference compensation plate 50 for compensating for phase differences in the thickness direction. Therefore, when the object being inspected 2 has a phase difference in the thickness direction or other factors that cause a phase difference in the thickness direction within the field of view, the phase difference in the tilt direction within the field of view can be compensated, and observation can be performed correctly over a larger range.

[0070] Furthermore, the inspection device 1 of this embodiment has a condenser lens 40 between the component 30 that produces parallel light and the phase difference compensation plate 50, thus suppressing the light diffusion that passes through the component 30 that produces parallel light.

[0071] In addition, the inspection device 1 of this embodiment has a reflective polarizer 15 between the polarizing filter 17 and the light source 13, which can improve the utilization efficiency of the light emitted by the light source 13.

[0072] Furthermore, before inspecting the polarizer for defects, the polarizing filter 17 is rotated by operating the rotating member 11 using the operating rod 19, thereby aligning the direction of the optical axis of the polarizing filter 17 with the direction suitable for inspection. That is, even if the object under inspection 2 has a film with a phase difference, such as a release liner, by adjusting the relationship between the optical axis of the release liner and the optical axis of the second region 17b of the polarizing filter 17, inspection can be performed using the first region 17a while eliminating the phase difference inherent in the release liner. This inspection method is particularly effective when using a polyethylene terephthalate film with a large phase difference as the release liner.

[0073] Furthermore, when the circular polarizer has a phase retardation film formed by a polymeric liquid crystal compound, the phase retardation film formed by the polymeric liquid crystal compound is usually thinner than the phase retardation film formed by other methods. However, according to the inspection device 1, even if the color unevenness defect caused by the phase difference value change of about a few nm present in the thin phase retardation film is reduced, the omission of the defect can be reduced.

[0074] The preferred embodiments of the present invention have been described above, but the present invention is not limited to any of the above embodiments. For example, in the above embodiments, the sliding support mechanism 20 includes a stage 21, a sliding guide 23A, a movable plate 25, and a glass plate 29, but the structure of the sliding support mechanism 20 can also be appropriately simplified. In addition, the reflective polarizer 15 can be omitted from the rotating mechanism 10. Furthermore, the reflective polarizer 15, the condenser lens 40, and the phase difference compensation plate 50 are also components used to further improve the inspection accuracy, so their use or omission can be determined according to the required level of inspection accuracy.

[0075] Furthermore, in the above embodiment, a scheme is shown in which the component 30 for producing parallel light is configured as a laminate of a plastic corrugated sheet 32 ​​having a through hole 33, but the structure of the component 30 for producing parallel light is not limited to this. For example, even if the wall of the interior space 34 is configured as a wall with an anti-reflective film, a wall coated with a light-absorbing material, or a wall composed of a combination of these, the desired parallel light can be obtained.

[0076] In this embodiment, the sliding guide 23A is designed as a rod, but it can be any other shape as long as it extends in one direction. For example, it can be a design in which multiple columns are arranged discretely in a row. In this case, the spacing between the columns is set to be sufficiently short than the length of the side of the movable plate 25 so that the sliding of the abutting movable plate 25 can be performed smoothly.

[0077] In addition, in this embodiment, the window portion 21a of the mounting platform 21 and the window portion 25a of the movable plate 25 are rectangular, but either window portion can be a shape other than a rectangle, or one side of the window portion can be connected to the outer periphery of the mounting platform 21 or the movable plate 25 when viewed from above, so that the mounting platform 21 or the movable plate 25 is in the shape of a "コ".

[0078] Furthermore, in this embodiment, an example is shown where an object 2, which is smaller than the window portion 25a of the movable plate 25, is inspected. However, the object 2 may also be larger than the window portion 25a. In this case, after the inspection is completed by bringing both sides of the object 2 against the positioning members 27A and 27B, the other sides of the object 2 are brought against the positioning members 27A and 27B for further inspection, thereby enabling the entire surface of the object 2 to be inspected.

[0079] Furthermore, in the above embodiment, the case where the inspection device 1 is placed on a horizontal platform has been described. However, the inspection device 1 can also be tilted at approximately 5° to 20° so that it is higher from the depth side observed by the inspector. In this case, it is possible to prevent the glass plate 29 and the object to be inspected 2 from moving away from the positioning members 27A and 27B when the movable plate 25 is slid. Alternatively, the inspection device 1 can be mounted on the wall at a 90° angle.

[0080] Industrial availability

[0081] This invention can be used to inspect circular polarizing plates for defects.

Claims

1. An inspection apparatus for inspecting a film-like object having a circular polarizing plate for defects, characterized in that, The inspection device includes: Polarizing filter; A light source, which is disposed on one side of the polarizing filter; A rotating component that can rotate the polarizing filter in its in-plane direction with the direction in which the polarizing filter is arranged with the light source as the axial direction; A sliding support mechanism, disposed on the other side of the polarizing filter, supports the object being inspected in sliding in its in-plane direction in a direction substantially orthogonal to the axis direction during inspection. as well as A component for producing parallel light is disposed between the polarizing filter and the sliding support mechanism to remove diffused light from the light emitted from the light source and transmitted through the polarizing filter.

2. The inspection device according to claim 1, characterized in that, The inspection device also includes a phase difference compensation plate between the component that produces parallel light and the sliding support mechanism to compensate for the phase difference in the thickness direction.

3. The inspection device according to claim 2, characterized in that, The inspection device also includes a focusing lens between the component that produces parallel light and the phase difference compensation plate.

4. The inspection device according to claim 1, characterized in that, The inspection device also includes a reflective polarizer between the polarizing filter and the light source.

5. The inspection device according to claim 1, characterized in that, The component for producing parallel light has: An internal space through which light emitted by the light source passes toward the object being inspected; and A through hole connects the interior space to the exterior of the component that produces parallel light, guiding light emitted by the light source that is not directed toward the object being inspected toward the exterior.

6. The inspection device according to claim 1, characterized in that, The sliding support mechanism includes: a stage arranged with its mounting surface substantially parallel to the surface of the polarizing filter; and a guide arranged to extend in one direction on the mounting surface. The stage is provided with a window that allows light emitted from the light source and passing through the polarizing filter to pass through.

7. The inspection device according to claim 6, characterized in that, The sliding support mechanism also includes a movable plate, the thick portion of which can abut against the guide, and the movable plate can slide on the mounting surface along the extending direction of the guide. The movable plate is provided with a window that allows the light to pass through.

8. The inspection device according to claim 1, characterized in that, The object being inspected has a release film with a phase difference that is attached to the circular polarizer. The polarizing filter is configured as two regions with different optical axis directions when viewed from above.

9. The inspection device according to any one of claims 1 to 8, characterized in that, The circular polarizer has a phase retardation film formed by a polymeric liquid crystal compound.

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