Method for inspecting light-transmissive laminate

Abstract

The present application provides a kind of light transmission laminated body inspection method of detecting extra tiny foreign matter compared with the past.The present application light transmission laminated body inspection method is carried out transmission inspection in the state of fixing light transmission laminated body in the air piece by piece, detects the defect of 8 µm~50 µm size in light transmission laminated body.For example, the detection of defect includes the following steps: the focal point of the optical system of specified magnification is aligned with the surface of the first main surface of light transmission laminated body, and the optical system is scanned to light transmission laminated body, and the XY coordinate diagram of defect is made; the focal point of optical system is offset from the surface of the first main surface of light transmission laminated body to the inside of thickness direction by a specified distance, and the XY coordinate diagram of another defect is made by scanning the optical system to light transmission laminated body; and, the XY coordinate diagram of defect made is integrated.

Description

[0001] This application is a divisional application of the invention patent application filed on February 16, 2021, with application number 202180016062.X and invention title "Inspection Method for Light Transmittant Laminated Structures". Technical Field

[0002] This invention relates to a method for inspecting light-transmitting laminates. Background Technology

[0003] In order to prevent image display defects, foreign objects must be removed from the optically transmissive laminates (e.g., optical components, optical laminates, optical films, optically transmissive adhesive sheets) used in image display devices. Therefore, these optically transmissive laminates are typically used for foreign object inspection. Foreign object inspection is typically a transmission inspection performed while conveying a long strip of the optically transmissive laminate, in which foreign objects and / or defects can be identified as dark spots. In recent years, the display performance requirements for image display devices have become exceptionally high, resulting in exceptionally high requirements for the accuracy of foreign object inspection of optically transmissive laminates. Specifically, previously, detecting foreign objects and / or defects of approximately 50µm was acceptable, but now there is a need to detect foreign objects and / or defects of approximately 10µm. However, for foreign object inspection performed while conveying a long strip of material, detecting such small foreign objects and / or defects is extremely difficult.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-062165 Summary of the Invention

[0007] The technical problem that the invention will solve

[0008] In order to solve the aforementioned problems, the main objective of this invention is to provide an inspection method for light-transmitting laminates that can detect foreign objects and / or defects that are significantly smaller than those in the past.

[0009] Means for solving technical problems

[0010] The inspection method of the light-transmitting laminate of the present invention involves performing a transmission inspection while fixing each piece of the light-transmitting laminate in mid-air, and detecting defects of 8µm to 50µm in the light-transmitting laminate.

[0011] In one embodiment, the detection of the defect includes the following steps: focusing an optical system with a predetermined magnification onto the surface of the first main surface of the light-transmitting laminate, and scanning the light-transmitting laminate using the optical system to create an XY coordinate map of the defect; shifting the focus of the optical system from the surface of the first main surface of the light-transmitting laminate inward in the thickness direction by a predetermined distance, and scanning the light-transmitting laminate using the optical system to create an XY coordinate map of another defect; and integrating the created XY coordinate maps of the defects.

[0012] In one embodiment, the detection of the defect includes the following steps: shifting the focal point of the optical system inward by a predetermined distance in the thickness direction of the light-transmitting laminate and scanning the light-transmitting laminate using the optical system, repeating the operation a predetermined number of times to generate an XY coordinate map of a predetermined number of defects.

[0013] In one embodiment, the detection of the defect includes the following steps: determining the position of the defect in the thickness direction using an optical system with a magnification higher than the specified magnification, only for the coordinates of the defect occurring in the integrated XY coordinate diagram of the defect.

[0014] In one embodiment, determining the position of the defect in the thickness direction includes the following steps: focusing the high-magnification optical system onto the surface of the first master surface of the light-transmitting laminate; and moving the focus inward in the thickness direction of the light-transmitting laminate to measure the distance from the surface of the first master surface to the defect.

[0015] In one embodiment, the specified distance is 10µm to 100µm.

[0016] In one embodiment, the specified multiplier is 5 times or less. In another embodiment, the high multiplier is 10 times or more.

[0017] In one embodiment, the light-transmitting laminate is selected from optical thin films, adhesive sheets, and combinations thereof. In another embodiment, the optical thin film is selected from polarizing plates, retardation plates, and laminates comprising these.

[0018] In one embodiment, the thickness of the light-transmitting laminate is less than 300 µm.

[0019] In one embodiment, the inspection method detects the defect in the area where, when scanned by an optical system at the specified magnification, the variation in the thickness direction of the first principal surface of the light-transmitting laminate is within ±10µm per 1000µm of the scanning distance.

[0020] In one embodiment, the inspection method involves detecting the defect in a region where the deflection angle of the light-transmitting laminate is within ±0.57° relative to the horizontal direction.

[0021] In one embodiment, the inspection method involves detecting the defect while the light-transmitting laminate is horizontally mounted.

[0022] In one embodiment, the inspection method involves detecting the defect while the opposing ends of the non-product area in the light-transmitting laminate are fixed to a pair of support members that can be relatively close to or far apart.

[0023] In one embodiment, the pair of support members are slidable and are given potential energy in a direction that moves them away from each other.

[0024] In one embodiment, the light-transmitting laminate includes an adhesive layer, and the light-transmitting laminate is fixed to the pair of support members through the adhesive layer. In one embodiment, the fixing of the light-transmitting laminate through the adhesive layer includes the following steps: peeling off a separator at one end of the light-transmitting laminate and attaching it to one of the support members through the exposed adhesive layer; then peeling off a separator at the other end and attaching it to the other support member through the exposed adhesive layer.

[0025] In one embodiment, the light-transmitting laminate includes a surface protective film temporarily adhered to at least one surface in a peelable manner, and the inspection method includes the step of temporarily peeling off the surface protective film after the light-transmitting laminate is fixed to the pair of support members. In another embodiment, the inspection method includes the step of temporarily adhering, after the defect is detected, the temporarily peeled surface protective film or another surface protective film different from the surface protective film to at least one surface of the light-transmitting laminate in a peelable manner.

[0026] According to another aspect of the present invention, a light-transmitting laminate is provided for an inspection method of the light-transmitting laminate. The light-transmitting laminate further comprises at least one reflective protective film temporarily adhered to the first main surface in a peelable manner. The reflective protective film has the function of reflecting illumination light and transmitting inspection light when the focal point of the optical system at a predetermined magnification is aligned with the surface of the first main surface.

[0027] In one embodiment, the reflective protective film satisfies the following relationship:

[0028] y≥0.0181x-11.142

[0029] Here, x is the absolute value of the detection wavelength in the wavelength region of 650nm~800nm, and y is the absolute value of the reflectance.

[0030] In one embodiment, the light-transmitting laminate further comprises a surface protective film temporarily adhered to the surface of the reflective protective film in a peelable manner.

[0031] In one embodiment, the light-transmitting laminate further comprises a hard coating formed on the surface of the reflective protective film.

[0032] In one embodiment, the light-transmitting laminate is provided with an identification mechanism that can identify the inspected area after inspection.

[0033] Invention Effects

[0034] According to the inspection method of the light-transmitting laminate according to an embodiment of the present invention, by performing transmission inspection while fixing the light-transmitting laminate piece by piece in mid-air, it is possible to detect foreign objects and / or defects that are much smaller than before (e.g., about 8µm in size). Attached Figure Description

[0035] Figure 1 This is a schematic side view illustrating an example of a transmission inspection according to an embodiment of the present invention.

[0036] Figure 2 (a) to (d) are schematic side views illustrating an example of a procedure for fixing a light-transmitting laminate to a support member in the detection of defects in a transmission inspection.

[0037] Figure 3 This is a schematic diagram illustrating the focus alignment of the imaging component during defect detection in transmission inspection.

[0038] Figure 4 This is a schematic three-dimensional diagram illustrating the XY plane scanning of a light-transmitting laminate using an imaging component during defect detection in transmission inspection.

[0039] Figure 5 This is a conceptual diagram illustrating an example of the XY coordinate diagram of a defect in the detection of defects during transmission inspection.

[0040] Figure 6 This is a conceptual diagram illustrating an example of integrating an XY coordinate graph of a specified number of defects in the detection of defects during transmission inspection.

[0041] Figure 7 (a) to (c) are schematic top views illustrating the identification mechanism that can be installed on a light-transmitting laminate. Detailed Implementation

[0042] The following description refers to embodiments of the present invention, but the present invention is not limited to these embodiments. Furthermore, the accompanying drawings are schematic illustrations and do not represent accurate depictions of actual conditions.

[0043] A. An overview of the examination methods for transmissive laminates

[0044] The inspection method for light-transmitting laminates according to embodiments of the present invention involves performing a transmission inspection while each light-transmitting laminate is fixed in mid-air. Figure 1This is a schematic side view illustrating an example of transmission inspection. Transmission inspection includes, for example, the following steps: using an optical system to obtain an image of a translucent laminate 10 laterally mounted on a pair of support members 20, 20. The optical system includes, for example, an imaging component 30 disposed on one side of the translucent laminate 10 (above in the example) and capable of acquiring an image of the translucent laminate; and a light source 40 disposed on the other side of the translucent laminate 10 (below in the example) and emitting illumination light that illuminates the translucent laminate 10. Alternatively, the imaging component 30 may be disposed below the translucent laminate 10 and the light source 40 above the translucent laminate 10. The imaging component 30 captures an image of transmitted light (inspection light), in which foreign objects and / or defects (hereinafter referred to simply as foreign objects or defects for the context) can be identified as dark spots. More specific embodiments of transmission inspection will be described later. By performing transmission inspection while each optically transmissive laminate is fixed in mid-air, defects of 8µm to 50µm in size can be detected in the optically transmissive laminate, preferably 8µm to 30µm, more preferably 8µm to 20µm, more preferably 8µm to 15µm, and most preferably about 10µm. Conventionally, foreign matter inspection of optically transmissive laminates, such as optical films, is performed while conveying a long strip of material. This method of foreign matter inspection is practically unable to detect small foreign matter (represented to be less than 50µm). Furthermore, previously, detecting foreign matter of approximately 50µm in size was acceptable, so no particular problems arose in foreign matter inspection performed via strip conveying. However, with the increasing precision of image display devices, there is now a new demand for detecting foreign matter of approximately 10µm in size. The inventors have actively researched this problem and found that the inability to obtain a correct image using the imaging component may be due to strip vibration and / or vibration of the conveying device during transport. Furthermore, trial and error revealed that by cutting the light-transmitting laminate into single sheets and performing transmission inspection while these single sheets were fixed in mid-air (i.e., without being mounted), not only could the adverse effects of belt vibration and / or conveyor vibration during transport be eliminated, but also the adverse effects of foreign objects on the mounting surface could be eliminated. This resulted in extremely high-precision foreign object inspection, capable of detecting foreign objects and / or defects as small as approximately 10µm. Therefore, this invention solves a novel problem never before encountered.

[0045] B. Light-transmitting laminate

[0046] The light-transmitting laminate can be any suitable light-transmitting laminate required for foreign object inspection. Specific examples include optical films, adhesive sheets, and combinations thereof (e.g., optical films with an adhesive layer). Examples of optical films include polarizing plates, retardation plates, conductive films for touch panels, surface-treated films, and laminates formed by stacking these suitable materials for a specific purpose (e.g., circular polarizing plates for anti-reflection, polarizing plates for touch panels with conductive layers). An adhesive sheet represents an adhesive and a release film temporarily attached to at least one side thereto. The light-transmitting laminate can be an optical film with an adhesive layer. The thickness of the light-transmitting laminate is preferably 300 µm or less, more preferably 280 µm or less, and more preferably 250 µm or less. According to embodiments of the present invention, even in the thin light-transmitting laminate, minute foreign objects can be detected well. The lower limit of the thickness of the light-transmitting laminate can be, for example, 30 µm.

[0047] A translucent laminate can be manufactured, for example, by laminating the layers of the translucent laminate using a roll-to-roll process. The translucent laminate has a first main surface and a second main surface. The first main surface represents the surface opposite to the image display unit to which the translucent laminate can be adhered; the second main surface represents the surface on the image display unit side, more specifically, the surface of the adhesive layer. The resulting strip-shaped translucent laminate is cut to a specified size for foreign object inspection. This size represents the size at which multiple final products can be obtained. After inspection, the translucent laminate can be cut to the final product size and shipped.

[0048] In one embodiment, when the light-transmitting laminate is used for foreign object inspection, a reflective protective film may be temporarily adhered to the first main surface in a peelable manner. Depending on the type and structure of the light-transmitting laminate, some imaging components (e.g., when the light-transmitting laminate includes a low-reflection layer (AR layer)) may be unable to autofocus on the first main surface of the light-transmitting laminate. However, by temporarily adhering the reflective protective film, even in such cases, the imaging component can still effectively autofocus on the first main surface of the light-transmitting laminate. The reflective protective film represents the function of reflecting and transmitting inspection light when the focus of an optical system at a specified magnification is aligned with the surface of the first main surface of the light-transmitting laminate. In one embodiment, the reflective protective film satisfies the following relationship:

[0049] y≥0.0181x-11.142

[0050] Here, x is the absolute value of the detection wavelength in the wavelength region of 650nm to 800nm, and y is the absolute value of the reflectivity. With this configuration, the autofocus function of the imaging component can be performed better. The reflective protective film can be constructed in any suitable manner as long as it has the aforementioned function. Specifically, the reflective protective film can be constructed using, for example, the cyclic olefin resin described in

[0031] of Japanese Patent Application Publication No. 2019-099751. Examples of cyclic olefin resins include, for example, polynorbornene. Commercially available cyclic olefin resins can also be used. Specific examples of commercially available products include Zeonor and ZEONEX manufactured by ZEON Japan, ARTON manufactured by JSR, APEL manufactured by Mitsui Chemicals, and TOPAS manufactured by TOPAS ADVANCED POLYMERS. The cyclic olefin resin film preferably contains 50% by weight or more of the cyclic olefin resin. In one embodiment, a hard coating may also be formed on the surface of the reflective protective film. By forming a hard coating, scratches and foreign objects can be prevented from adhering to the reflective protective film, thus enabling more precise foreign object inspection and accurate detection of minute foreign objects and / or defects.

[0051] Multiple reflective protective films can be temporarily attached to accommodate a specified number of inspections. For example, if two foreign object inspections are specified, by attaching two reflective protective films, and only peeling off one outer reflective protective film before the second inspection, damage to the inner reflective protective film and foreign objects adhering to it can be prevented. This allows for more precise multiple foreign object inspections. Alternatively, even when multiple inspections are specified, only one reflective protective film can be temporarily attached.

[0052] In one embodiment, a surface protective film can be temporarily adhered to the surface of the reflective protective film (the outermost reflective protective film surface when multiple reflective protective films are present) in a peelable manner. Temporarily adhering the surface protective film prevents scratches on the reflective protective film and foreign matter from adhering to it, thus enabling more precise foreign matter inspection. The surface protective film is essentially peeled off during inspection. After inspection, the surface protective film peeled off during inspection can be temporarily re-adhered to the surface of the light-transmitting laminate, or another surface protective film can be temporarily adhered in a peelable manner.

[0053] Reflective protective films and surface protective films can be temporarily adhered to light-transmitting laminates by roll-to-roll (i.e., before cutting) or temporarily adhered after cutting.

[0054] C. Specific implementation method of the inspection method for transmissive laminates

[0055] C-1. Fixed in mid-air

[0056] The detection of defects in transmission inspection will be described in more detail below. In defect detection, as described above, transmissive laminates are fixed in mid-air one by one. Transmissive laminates can be, for example, as described... Figure 1 As shown, the material is fixed in mid-air by being horizontally mounted on a pair of support members. In the light-transmitting laminate, the opposite ends belonging to the non-product area can be fixed to the support members. Typically, the light-transmitting laminate includes an adhesive layer, and the light-transmitting laminate can be fixed to the support members through this adhesive layer. Figure 2 (a)~ Figure 2 (d) is a schematic side view illustrating an example of a procedure for fixing a light-transmitting laminate to a support member. In this series of procedures, ideally, the light-transmitting laminate has a reflective protective film 50 and a surface protective film 60 temporarily adhered to the first main surface 10a in a peelable manner. First, as... Figure 2 As shown in (a), the separator at one end 10c of the light-transmitting laminate, which belongs to the non-manufacturing area, is peeled off, exposing the adhesive layer. End 10c is then adhered to the support member 20 through this adhesive layer. Next, as... Figure 2 As shown in (b), the separator of end 10d, which belongs to the non-manufactured area and is opposite to end 10c, is peeled off, exposing the adhesive layer. End 10d is then adhered to the support member 20 through this adhesive layer. By using the adhesive layer to adhere the end of the light-transmitting laminate to the support member, it can be easily fixed without the use of additional fixing fixtures. When ends 10c and 10d are adhered, as shown... Figure 2 As shown in (c), the separators are completely removed. Here, the reflective protective film 50 and the surface protective film 60 not only prevent scratches and / or foreign matter from adhering to the light-transmitting laminate, but also function as reinforcement materials when removing the separators and bonding ends. After the above procedure, the light-transmitting laminate is horizontally mounted on the support member. Next, as... Figure 2As shown in (d), after peeling off the surface protective film 60, the light-transmitting laminate 10 with the reflective protective film 50 temporarily attached is used for foreign object inspection. By fixing the light-transmitting laminate to the support member before peeling off the surface protective film (i.e., fixing the light-transmitting laminate to the support member while the surface protective film is temporarily attached), the rigidity (toughness) of the light-transmitting laminate can still be maintained after the separation member is peeled off, making it easy to handle. As a result, since wrinkles and the like can be prevented, foreign object inspection can be performed with high precision, and minute foreign objects and / or defects can be accurately detected. Furthermore, by performing foreign object inspection in the state of horizontally assembling the light-transmitting laminates one by one, the effects of vibration caused by transport and / or vibration of the transport device can be eliminated. Therefore, even after peeling off the surface protective film, foreign object inspection can still be performed with high precision, and minute foreign objects and / or defects can be accurately detected. Moreover, by peeling off the surface protective film, foreign objects on the surface protective film will not be detected. Therefore, by utilizing the synergistic effect with the above-mentioned effects, foreign object inspection can be performed with even higher precision. In one embodiment, as described in section B, multiple reflective protective films may also be temporarily adhered. In this case, the surface protective films are peeled off during the first foreign object inspection, and one reflective protective film may be peeled off for each subsequent foreign object inspection.

[0057] In this embodiment, a pair of support members 20, 20 are configured to be able to move closer or further apart relative to each other. In one embodiment, the support members are configured to be slidable and are endowed with potential energy in a direction that moves them further apart. Specifically, as... Figure 2 (b)~ Figure 2 As shown in (d), one side of the support member (the right side in the example diagram) is fixed, while the other side (the left side in the example diagram) is slidable and is given potential energy in a moving away direction using an elastic member (e.g., a spring). With this configuration, appropriate tension (force) can be applied to the light-transmitting laminate, allowing it to be in a stretched, erected state. As a result, wrinkles and strain in the light-transmitting laminate are significantly suppressed, enabling more precise foreign object inspection and accurate detection of minute foreign objects and / or defects. Tension can be controlled by adjusting the strength of the spring itself and the tightening of the spring's fixing screw. Alternatively, both support members can be slidable, and potential energy can be applied to both sides in a moving away direction using elastic members.

[0058] C-2. Defect Detection

[0059] Defect detection, as described above, typically involves using methods such as... Figure 1 The optical system shown (including the imaging component 30 and the light source 40) is used. A detailed explanation follows. First, as... Figure 3As shown on the left, the focal point of an optical system (essentially the imaging assembly 30) with a specified magnification (hereinafter sometimes referred to as low magnification) is aligned with the surface of the first principal surface 10a of the light-transmitting laminate 10. In this state, according to Figure 4 The image shows that the imaging component 30 scans the entire plane (XY plane) of the light-transmitting laminate 10 to create an XY coordinate map of defects (first XY coordinate map). As described in section A, defects are identified as dark spots. Therefore, in the first XY coordinate map, defects near the first principal surface 10a of the light-transmitting laminate 10 (up to a predetermined distance from the first principal surface to the inner side in the thickness direction) will be identified, for example, as... Figure 5 The image shown contains dark spots. Furthermore, sometimes the first XY coordinate map alone cannot detect minute defects in deeper locations along the thickness direction (near the second master surface). To address this, according to an embodiment of the present invention, as described later, defect detection is performed by offsetting a predetermined distance P from the surface of the first master surface inwards along the thickness direction, thus accurately detecting minute defects throughout the thickness direction of the transmissive laminate.

[0060] Next, as Figure 5 As shown in the central portion, the focal point of the imaging component 30 is offset by a predetermined distance P from the surface of the first main surface 10a of the light-transmitting laminate 10 in the thickness direction (Z direction), aligning the focal point with a predetermined position inside the thickness direction of the light-transmitting laminate 10. In this state, the same method as described above is followed. Figure 4 The image shows an XY coordinate diagram (second XY coordinate diagram) of defects created by scanning the entire XY plane of the light-transmitting laminate 10 using the imaging component 30. In the second XY coordinate diagram, defects located near a predetermined position (from that predetermined position to a predetermined distance) inside the thickness direction of the light-transmitting laminate 10 are identified as, for example, located near... Figure 5 Essentially, these are the starting points on the images at different locations. Furthermore, in this specification, the specified distance P is sometimes referred to as the shooting interval. The focus alignment of the shooting component can be achieved using any suitable means. For example, the shooting component itself can be moved in the Z direction, the focus distance of the shooting component can be changed by using a lens, or a combination of these means can be used. The illustrated example shows a form where the focus distance of the shooting component is changed by using a lens, etc.

[0061] Depending on the needs Figure 3 As shown on the right, the focus of the imaging component 30 is shifted a predetermined distance P in the thickness direction (Z direction) to align the focus with the next predetermined position inside the thickness direction of the light-transmitting laminate 10. In this state, the same procedure is followed as described above. Figure 4The imaging component 30 scans the entire XY plane of the light-transmitting laminate 10 to create an XY coordinate map of defects (a third XY coordinate map). This operation is repeated a predetermined number of times as needed to create a predetermined number of XY coordinate maps of defects. The imaging interval and the number of XY coordinate maps of defects to be created can be appropriately set according to the overall thickness of the light-transmitting laminate, the number of layers constituting the light-transmitting laminate, and the thickness of each layer. The imaging interval P can be, for example, 10µm to 100µm, and is preferably 20µm to 80µm, more preferably 40µm to 60µm. Using this configuration, all defects substantially existing in the thickness direction (therefore, all defects in the light-transmitting laminate) and their approximate locations can be detected without scanning the entire thickness direction with the imaging component. Figure 3 The diagram shows the form of making XY coordinate diagrams of 3 defects, but the number of XY coordinate diagrams of defects to be made is not limited to this, preferably 2 to 10, more preferably 3 to 8, and more preferably 4 to 6.

[0062] Next, the XY coordinate diagrams of the specified number of defects produced are integrated. For example... Figure 6 This example demonstrates how an integrated XY coordinate graph (combined XY coordinate graph) can be created by integrating the XY coordinate graphs of five defects. (The example is repeated in the original text.) Figure 6 By integrating the various image data, defects existing in each XY coordinate map can be represented on a common XY coordinate system. This allows the creation of an integrated XY coordinate map. In the integrated XY coordinate map, virtually all defects in the transmissive laminate are represented as XY coordinates (two-dimensional coordinates).

[0063] In the fabrication of the integrated XY coordinate map as described above, the specified magnification (low magnification) of the imaging component is preferably less than 10x, and more preferably less than 5x. The lower limit of this magnification can be, for example, 1.5x. As long as the magnification is within this range, a wide range of light-transmitting laminates can be efficiently captured, resulting in the efficient fabrication of an integrated XY coordinate map.

[0064] Next, the depth of the defect (its position in the thickness direction of the transmissive laminate) is measured. It is difficult to detect defects by covering the entire plane of the transmissive laminate and the entire thickness direction; even if it were possible, it would be impractical considering cost, time, and efficiency. Therefore, in this embodiment, the position of the defect in the thickness direction is determined only for the defect occurrence coordinates in the integrated XY coordinate diagram. As described above, in the integrated XY coordinate diagram, since virtually all defects in the transmissive laminate are represented by two-dimensional coordinates, the positions of virtually all defects in the thickness direction in the transmissive laminate can be detected by determining the position of the defect in the thickness direction only for the defect occurrence coordinates.

[0065] The determination of defect depth includes the following steps: aligning the focus of the imaging component with the surface of the first master surface of the light-transmitting laminate; and moving the focus inward along the thickness direction of the light-transmitting laminate, and measuring the distance from the surface of the first master surface to the defect. Specifically, the focus of the imaging component can be moved along the thickness direction, the position with high contrast can be identified as the focus position, and the distance from the surface of the first master surface to the focus position can be taken as the position of the defect in the thickness direction. By detecting the correct position of the defect in the thickness direction, the inspection efficiency and shipping efficiency of the products can be significantly improved.

[0066] In the defect depth measurement described above, the magnification (high magnification) of the imaging component is preferably 10x or more, and more preferably 20x or more. The upper limit of this magnification can be, for example, 50x. As long as the magnification is within this range, the location of minute defects in the thickness direction can be reliably detected.

[0067] The determination of defect depth has been described in, for example, Japanese Patent Application Publication No. 2001-124660, Japanese Patent Application Publication No. 2004-077261, and Japanese Patent Application Publication No. 2009-250893. This specification incorporates the descriptions in these publications by reference.

[0068] In one embodiment, defect detection can be performed in the region where the variation in the thickness direction (Z direction) of the first principal surface of the light-transmitting laminate is within ±10µm per 1000µm of scanning distance when scanning with the imaging component, and preferably within ±8µm. In another embodiment, defect detection can be performed in the region where the deflection angle of the light-transmitting laminate is within ±0.57° relative to the horizontal direction, and preferably within ±0.50°. That is, in any embodiment, defect detection can be performed in a region where the deflection of the light-transmitting laminate is very small. With this configuration, the focus of the imaging component can be accurately aligned with the first principal surface of the light-transmitting laminate (which, consequently, is the subsequent alignment with a predetermined position inside the thickness direction). As a result, the position of minute defects in the thickness direction can be accurately detected. The region where the deflection of the light-transmitting laminate is very small can be achieved by the method of fixing the light-transmitting laminate described in item C-1. Furthermore, when the variation and / or deflection angle exceed the aforementioned range, it may be impossible to perform a proper transmission inspection, resulting in areas in the light-transmitting laminate that cannot be inspected. In such cases, by providing a means to identify inspected areas in the light-transmitting laminate as described later, it is possible to prevent the shipment of non-inspected areas as finished products.

[0069] Transmissive inspection (defect detection) can then be performed using the above method. After inspection, the transmissive laminate, as described above, is ready to be cut to the final product size and shipped. Also as described above, the peeled surface protective film can be temporarily reattached to the transmissive laminate in a peelable manner after inspection, if required.

[0070] In one embodiment, an identification mechanism is provided on the inspected light-transmitting laminate (essentially a surface protective film or reflective protective film remaining on the first main surface side of the light-transmitting laminate) to identify the inspected area. For example, when the deflection angle of the light-transmitting laminate is very large relative to the horizontal direction, areas that cannot be inspected through the light-transmitting laminate may occur. Alternatively, depending on the fixing state of the light-transmitting laminate using the support member, there may be cases where the inspection area deviates from the set point. By providing a means to identify the inspected area, even in the aforementioned situations, the situation of shipping non-inspected areas as finished products can be prevented. The identification mechanism can be formed, for example, by marking on the light-transmitting laminate using a plotter that moves in conjunction with the imaging component. Specific forms of the identification mechanism include, for example, straight or dashed lines surrounding the inspected area, intersecting marks, or dots at regular intervals.

[0071] Reference Figure 7 (a)~ Figure 7 (c) Provide specific details regarding the identification mechanism. For example, such as... Figure 7 As shown in (a), when the fixation of the light-transmitting laminate 10 using the support member 20 has deviated, the scanning of the imaging assembly is performed in the XY direction (the long side direction and the short side direction when the light-transmitting laminate 10 is correctly fixed), therefore... Figure 7 As shown in (b), the inspected area 70a will deviate from the product area 80. If the identification mechanism is not marked, it will... Figure 7 (c) The possibility of shipping non-inspection areas marked with "×" as products is eliminated, but the non-inspection areas can be identified by the marking and identification mechanism 70b, thus preventing the situation of shipping non-inspection areas as products.

[0072] Industrial availability

[0073] The inspection method for light-transmitting laminates according to embodiments of the present invention is suitable for detecting foreign matter such as optical films and adhesive sheets during the manufacturing process of image display devices.

[0074] Explanation of reference numerals in the attached figures

[0075] 10: Light-transmitting laminates

[0076] 10a: First Main Face

[0077] 10c, 10d: End

[0078] 20: Supporting components

[0079] 30: Shooting Components

[0080] 40: Light source

[0081] 50: Reflective protective film

[0082] 60: Surface protective film

[0083] 70a: Area inspected

[0084] 70b: Identification Agency

[0085] 80: Product Area

[0086] P: Specified distance (shooting interval)

Claims

1. A light-transmitting laminate, characterized in that, It has a first principal face and a second principal face. It includes at least one reflective protective film that is temporarily adhered to the first main surface in a peelable manner. The reflective protective film has the function of reflecting illumination light and transmitting inspection light when the focal point of an optical system with a specified magnification is aligned with the surface of the first main surface. It is used for transmission inspection to detect defects in the size of 8µm to 50µm. It is equipped with an identification mechanism that can identify the inspected area after the transmission inspection. The identification mechanism is a straight line or dashed line, intersecting mark, or points at certain intervals that surround the inspected area.

2. The light-transmitting laminate as described in claim 1, characterized in that, The reflective protective film satisfies the following relationship: y≥0.0181x-11.142 Here, x is the absolute value of the detection wavelength in the wavelength region of 650nm~800nm, and y is the absolute value of the reflectance.

3. The light-transmitting laminate as described in claim 1 or 2, characterized in that, It further includes a surface protective film that is temporarily adhered to the surface of the reflective protective film in a peelable manner.

4. The light-transmitting laminate as described in claim 1 or 2, characterized in that, It further comprises a hard coating formed on the surface of the reflective protective film.

Images