JP6948215B2 - Defect inspection equipment, defect inspection method, and film manufacturing method - Google Patents

Description

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

Defect inspection devices for detecting defects in optical films such as polarizing films and retardation films, and films used for battery separators are known. In this type of defect inspection device, the film is conveyed by the conveying unit, the inspection area of the film is irradiated with light by the light irradiation unit, the inspection area of the film is imaged by the imaging unit, and the defect inspection is performed based on the captured image. conduct. As the defect inspection device, for example, a device using an inspection optical system based on the normal transmission method (see Patent Document 1) and a device using an inspection optical system based on the cross Nicol transmission method (see Patent Document 2) are known. Has been done.

Japanese Unexamined Patent Publication No. 2012-167975 Japanese Unexamined Patent Publication No. 2007-21242

In defect inspection, it is desirable to detect defects in a plurality of different inspection optical systems (for example, normal transmission inspection optical system and cross Nicol inspection optical system) in order to detect defects more reliably. However, if these inspection optical systems are prepared separately, the introduction cost and the management cost increase. Therefore, integration of a plurality of inspection optical systems is desired.

Therefore, an object of the present invention is to provide a defect inspection apparatus, a defect inspection method, and a film manufacturing method in which different inspection optical systems are integrated.

The defect inspection device according to one aspect of the present invention is a film defect inspection device, and includes a light irradiation unit that outputs inspection light that irradiates the inspection region of the film, and an imaging unit that images the inspection region. At least one of the light irradiation unit and the imaging unit has a filter unit that selectively passes light in a predetermined polarization direction, and the filter unit is configured to be able to adjust the predetermined polarization direction. ..

The defect inspection method according to another aspect of the present invention is a film defect inspection method, which comprises an inspection light irradiation step of irradiating the inspection region of the film with inspection light by a light irradiation unit and an imaging of the inspection region by an imaging unit. The light irradiation unit and at least one of the imaging unit have a filter unit that selectively passes light in a predetermined polarization direction, and the filter unit has the predetermined polarization direction. It is configured to be adjustable.

In the defect inspection apparatus and the defect inspection method, the inspection area is imaged by the imaging unit in a state where the inspection area of the film is irradiated with the inspection light by the light irradiation unit. Therefore, the imaging unit can acquire an inspection image of the inspection area illuminated by the inspection light from the light irradiation unit. At least one of the light irradiation unit and the imaging unit has a filter unit that selectively passes light in a predetermined polarization direction, and the filter unit is configured so that the predetermined polarization direction can be adjusted. Therefore, it is possible to obtain inspection images in different inspection states by adjusting the predetermined polarization direction with the filter unit. That is, different inspection optical systems can be integrated in one defect inspection device, and by adjusting the polarization direction of the light selectively passed by the filter unit, defect inspection can be performed in each of the different inspection optical systems. ..

The defect inspection apparatus and the filter unit in the defect inspection method may have a liquid crystal filter configured by providing a linear polarizing film on one side of a liquid crystal cell. In this case, the polarization direction of the light passing through the liquid crystal filter can be adjusted in a short time (for example, 0.1 msec to 25 msec) depending on whether or not a voltage is applied to the liquid crystal filter.

The film in the defect inspection apparatus according to one embodiment is an optical film having linearly polarized light characteristics, and the light irradiation unit includes a light source and a filter unit arranged between the light source and the film. You may. In the defect inspection method according to the embodiment, the film is an optical film having linear polarization characteristics, and the light irradiation unit passes the light from the light source through the filter unit to transmit the inspection light in the predetermined polarization direction. In the output and the inspection light irradiation step, the predetermined polarization direction of the inspection light may be adjusted by the filter unit.

In this case, since the predetermined polarization direction of the inspection light is adjusted, the defect inspection of the optical film having the linear polarization characteristic can be performed not only in the parallel Nicol state but also in the cross Nicol state or the half cross Nicol state. In the present specification, in the parallel Nicol state, the two polarization directions (or the polarization direction and the polarization axis) are substantially parallel, in other words, the angle formed by the two polarization directions (or the polarization direction and the polarization axis) is 0. It means a state of ° or more and 1 ° or less, preferably 0 °, and the cross Nicol state means that the angles formed by the two polarization directions (or the polarization direction and the polarization axis) are substantially parallel to each other. In other words, it means a state of 85 ° or more and 105 ° or less, preferably 90 °, and the half-cross Nicol state is an angle formed by two polarization directions (or a polarization direction and a polarization axis). Means a state in which is greater than 1 ° and less than 85 °.

In the defect inspection apparatus according to one embodiment, the film is an optical film having linear polarization characteristics, and the light irradiation unit uses a light source and a first polarized light whose polarization directions are orthogonal to each other. An optical path of the first polarized light separated by the polarization separating element and arranged on the optical path of the second polarized light separated by the polarization separating element and the polarization separating element separated into the second polarized light. An optical path synthesizer that synthesizes the light into the optical path of the second polarized light, an optical system that guides the monopolarized light separated by the polarization separating element to the optical path synthesizer, and the first polarized light guided by the optical system. The film is arranged on the optical path of the second polarized light, and the filter unit selectively passes the first polarized light. And the case where the second polarized light is selectively passed through may be switched.

In this configuration, the optical film has a linearly polarized light property that allows the first polarized light to pass through. When the filter unit selectively passes the first polarized light, the output light from the light source is separated into the first polarized light and the second polarized light by the polarization separating element, and then the separated first polarized light and the second polarized light are separated. The optical path of light is synthesized by the optical path synthesizer and output toward the film to be inspected. Therefore, when the filter unit passes the first polarized light, unpolarized inspection light is output from the light irradiation unit. Since the unpolarized inspection light includes the first polarized light, it is possible to inspect an optical film having linearly polarized light characteristics in a parallel Nicol state. When the filter unit selectively passes the second polarized light, when the output light from the light source is separated into the first polarized light and the second polarized light by the polarization separating element, the separated first polarized light is separated by the filter unit. It is blocked. Therefore, only the second polarized light is output from the optical path synthesizer. Therefore, when the filter unit selectively passes the second polarized light, the light irradiation unit outputs the inspection light as the second polarized light. Therefore, it is possible to inspect an optical film having linearly polarized light characteristics in a cross Nicol state.

The light irradiation unit is arranged between the polarization separation element and the optical path synthesis unit on the optical path of the second polarized light, is arranged in a cross-nicol state with respect to the film, and is the second polarized light. It may have a polarizing film that allows light to pass through.

The film in the defect inspection apparatus according to one embodiment is an optical film having linearly polarized light characteristics, and the imaging unit includes a camera and a filter unit arranged between the camera and the film. You may. In the defect inspection method according to one embodiment, the film is an optical film having linearly polarized light characteristics, and the imaging unit captures the inspection region of the film with a camera through the filter unit, and in the imaging step, the film is imaged. The predetermined polarization direction through which the filter unit passes may be adjusted.

In this case, by switching the polarization direction of the light passing through the filter unit, the arrangement relationship between the optical film having linearly polarized light characteristics and the filter unit can be changed between, for example, a parallel Nicol state and a cross Nicol state or a half cross Nicol state. It can be switched with. Therefore, for example, defect inspection of an optical film having linearly polarized light characteristics can be performed not only in a parallel Nicol state but also in a cross Nicol state or a half cross Nicol state.

The defect inspection apparatus according to one embodiment further includes a first linearly polarizing film arranged between the film and the imaging unit, and the film is a film having no linearly polarized light characteristics and has the above-mentioned light. The irradiation unit may have a light source and a filter unit arranged between the light source and the film. In the defect inspection method according to one embodiment, the film is a film having no polarization characteristics, and the light irradiation unit passes light from a light source through the filter unit to inspect light in a predetermined polarization direction. In the inspection light irradiation step, the filter unit switches the predetermined polarization direction of the inspection light, and in the imaging step, the imaging unit is arranged between the film and the imaging unit. The inspection area may be imaged through a first linear polarizing film.

In this case, by switching the polarization direction of the light passing through the filter unit, a parallel Nicol state can be formed between the first linear polarizing film and the filter unit, and a cross Nicole state or a half cross Nicole state can be formed. Therefore, even when the film does not have linearly polarized light characteristics, for example, a defect inspection in a parallel Nicol state and a defect inspection in a cross Nicol state or a half cross Nicol state can be performed.

The defect inspection apparatus according to one embodiment further includes a first linear polarizing film arranged between the imaging unit and the film, and the film is a film having no polarization characteristics and is irradiated with light. The unit is arranged on the optical path of the light source, the polarization separating element that separates the light from the light source into the first polarized light and the second polarized light whose polarization directions are orthogonal to each other, and the second polarized light. An optical path synthesizer that synthesizes the optical path of the first polarized light into the optical path of the second polarized light, an optical system that guides the first polarized light separated by the polarization separating element to the optical path synthesizer, and the second. On the optical path of the polarized light, the second polarized light is arranged between the polarization separating element and the optical path synthesizer, is arranged in a cross Nicol state with respect to the first linear polarizing film, and passes the second polarized light. It has a linear polarizing film and a filter unit arranged on the optical path of the first polarized light guided by the optical system, and the film is arranged on the optical path of the second polarized light and has the filter. The unit may be switched between a case where the first polarized light is selectively passed and a case where the second polarized light is selectively passed.

Also in this case, by switching the polarization direction of the light passing through the filter unit, it is possible to form a parallel Nicol state and a cross Nicol state between the first linear polarizing film and the filter unit. Therefore, even when the film does not have linearly polarized light characteristics, for example, a defect inspection in a parallel Nicol state and a defect inspection in a cross Nicol state can be performed.

The defect inspection apparatus according to one embodiment further includes a first linear polarizing film arranged between the light irradiation unit and the film, and the film is a film having no polarization characteristics, and the image pickup is performed. The unit may include a camera and a filter unit arranged between the camera and the film. In the defect inspection method according to one embodiment, the film is a film having no polarization characteristics, and the light irradiation unit passes light from a light source through the filter unit to inspect light in a predetermined polarization direction. Is output, the imaging unit images the inspection area of the film with a camera through the filter unit, and in the inspection light irradiation step, the inspection light is arranged between the light irradiation unit and the film. The optical film may be irradiated through the first linear polarizing film, and in the imaging step, the predetermined polarization direction through which the filter unit passes may be adjusted.

In this case, by switching the polarization direction of the light passing through the filter unit, a parallel Nicol state can be formed between the first linear polarizing film and the filter unit, and a cross Nicole state or a half cross Nicole state can be formed. Therefore, even when the film does not have linearly polarized light characteristics, for example, a defect inspection in a parallel Nicol state and a defect inspection in a cross Nicol state or a half cross Nicol state can be performed.

The defect inspection apparatus according to one embodiment has two light irradiation units, and the first light irradiation unit, which is one of the two light irradiation units, is opposite to the image pickup unit when viewed from the film. The second light irradiation unit, which is arranged on the side and is the other of the two light irradiation units, may be arranged on the same side as the image pickup unit when viewed from the film.

In this case, the first light irradiation unit and the image pickup unit form a transmission inspection optical system, and the second light irradiation unit and the image pickup unit form a reflection inspection optical system. Therefore, in the above configuration, the transmission inspection optical system and the reflection inspection optical system are integrated.

Another aspect of the present invention also relates to a film manufacturing method comprising a step of inspecting the film by the defect inspection method according to the other aspect of the present invention.

According to the present invention, the present invention can provide a defect inspection apparatus, a defect inspection method, and a film manufacturing method in which different inspection optical systems are integrated.

FIG. 1 is a schematic view of a defect inspection system including the defect inspection apparatus according to the first embodiment. FIG. 2 is a schematic view of the defect inspection device according to the first embodiment, and FIG. 2A shows a case where the liquid crystal filter (filter unit) included in the defect inspection device is in the OFF state. In the part (b) of 2, the liquid crystal filter (filter part) of the defect inspection device is in the ON state. FIG. 3 is a schematic view of the defect inspection device according to the second embodiment. FIG. 4 is a schematic view of the defect inspection device according to the third embodiment. FIG. 5 is a schematic view of the defect inspection device according to the fourth embodiment. FIG. 6 shows an inspection image in the first inspection in the verification experiment, the part (a) in FIG. 6 is an inspection image in the specular reflection inspection optical system, and the part (b) in FIG. 6 is a cross. This is an inspection image of the Nicole reflection inspection optical system. FIG. 7 shows an inspection image in the second inspection in the verification experiment, the part (a) in FIG. 7 is an inspection image in the specular reflection inspection optical system, and the part (b) in FIG. 7 is a cross. This is an inspection image of the Nicole reflection inspection optical system. FIG. 8 is a schematic view of the defect inspection device according to the fifth embodiment. FIG. 9 is a schematic view of the defect inspection device according to the sixth embodiment. FIG. 10 is a schematic view of the defect inspection device according to the seventh embodiment. FIG. 11 is a schematic view of the defect inspection device according to the eighth embodiment. FIG. 12 is a schematic view of the defect inspection device according to the ninth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are designated by the same reference numerals, and duplicate description will be omitted. The dimensional ratios in the drawings do not always match those described.

(First Embodiment)
FIG. 1 is a schematic view of a defect inspection system including the defect inspection apparatus according to the first embodiment. The defect inspection system 1 includes a transport unit 2 and a defect inspection device 3A, and the defect inspection device 3A arranged in the transport path while transporting the strip-shaped optical film 100 by the transport unit 2 in the longitudinal direction thereof. , Inspect the optical film 100 for defects.

The transport unit 2 has a transport roller R. In addition to the transport roller R, the transport unit 2 may include a tension applying device that applies tension to the optical film 100 to be transported. FIG. 1 shows XYZ Cartesian coordinates used for convenience of explanation. The X direction indicates the width direction of the optical film 100, and the Y direction indicates the transport direction of the optical film 100. The Z direction indicates a direction orthogonal to each of the X direction and the Y direction. In the description of other drawings, the same XYZ Cartesian coordinates may be used for description.

The defect inspection system 1 may include a marking device 4 as shown in FIG. The marking device 4 is a device that puts a mark M on the optical film 100 by using the defect information sent from the defect inspection device 3A. The marking device 4 has, for example, an arm extending along the width direction X of the optical film 100 and a marker head having a pen or the like. When the marker head moves on the arm in the width direction X, a mark M is attached on the optical film 100. The marking device 4 may be configured to be controlled by the defect inspection device 3A, or the marking device 4 itself may have a control unit such as a computer. Further, the marking device 4 may two-dimensionally code the defect information sent from the defect inspection device 3A and print it on the optical film 100.

The defect inspection performed by the defect inspection apparatus 3A includes a process of detecting defects that may occur during the manufacturing process (including a transfer process) of the optical film 100, and a defect map showing the positions of the inspected defects on the optical film 100. May include the process of creating. These defects include, for example, air bubbles, foreign matter and bright spots mixed in the optical film 100 in the manufacturing process of the optical film 100, foreign matter adhering to the optical film 100, and irregularities generated in the optical film 100.

The defect inspection device 3A according to the first embodiment will be described with reference to FIG. FIG. 2 is a schematic view of the defect inspection device 3A according to the first embodiment, and the portion (a) of FIG. 2 shows a case where the liquid crystal filter (filter portion) of the defect inspection device 3A is in the OFF state. In the part (b) of FIG. 2, the liquid crystal filter (filter part) included in the defect inspection device 3A is in the ON state.

FIG. 2 illustrates a polarizing film having linearly polarized light characteristics as the optical film 100 to be inspected by the defect inspection device 3A. In the following, unless otherwise specified, the optical film 100 as a polarizing film is a laminate of a film body 101, a protective film 102, and a protective film 103.

The film body 101 has linearly polarized light characteristics. In the first embodiment, the polarizing axis PA1 of the film body 101 is parallel to the Y direction, which is the transport direction of the optical film 100. Examples of the material of the film body 101 include PVA (Polyvinyl alcohol). The protective films 102 and 103 are attached to both sides of the film body 101. Examples of the materials of the protective films 102 and 103 include TAC (Triacetyl cellulose).

The optical film 100 may further have a film such as a protective film or a separate film on the surface of each of the protective films 102 and 103 opposite to the surface in contact with the film main body 101. A film such as a protective film or a separate film can be attached to the protective films 102 and 103 via, for example, an adhesive or an adhesive. Either one of the protective films 102 and 103 may be replaced with a film such as a separate film. An example of a material for a separate film and a protective film is PET (Polyethylene terephthalate). The protective film and the separate film are peeled off from the optical film 100 before and after the optical film 100 is attached to, for example, a liquid crystal panel or another optical film.

Hereinafter, the light polarized in the transport direction of the optical film 100 (the direction of the polarization axis PA1 of the film body 101) is referred to as the first polarized light, and the light polarized in the direction orthogonal to the first polarized light is referred to as the second polarized light. ..

The defect inspection device 3A includes a light irradiation unit 10A and an imaging unit 20A. The defect inspection device 3A may include a control device 30 that controls the light irradiation unit 10A and the image pickup unit 20A. Hereinafter, unless otherwise specified, a mode including the control device 30 will be described. The same applies to other embodiments.

The light irradiation unit 10A is arranged on the side opposite to the image pickup unit 20A when viewed from the optical film 100. The light irradiation unit 10A outputs the inspection light L to irradiate the optical film 100 to be inspected toward the inspection region A (see FIG. 1) of the optical film 100. The light irradiation unit 10A has a light source 11 and a liquid crystal filter 12, and outputs unpolarized light output from the light source 11 as inspection light L having a predetermined polarized state by passing through the liquid crystal filter 12. In FIG. 2, the polarization direction of the first polarized light is indicated by a double-headed arrow, and the polarization direction of the second polarized light is indicated by a black circle.

The light source 11 is unpolarized and is not limited as long as it can output light that does not affect the composition and properties of the optical film 100. Examples of the light source 11 are, for example, a metal halide lamp, a halogen transmission light, a fluorescent lamp, and the like. As shown in FIG. 1, the light source 11 may extend in the width direction of the optical film 100. Alternatively, the light irradiation unit 10A may include a plurality of light sources 11 and they may be arranged discretely along the width direction of the optical film 100.

In the first embodiment, the liquid crystal filter 12 selectively passes light in a predetermined polarization direction from the polarized light contained in the output light from the light source 11. The liquid crystal filter 12 is in the ON state when a constant voltage is applied, and is in the OFF state when the constant voltage is not applied. By switching the ON / OFF state of the liquid crystal filter 12, the polarization direction of the light passing through the liquid crystal filter 12 can be switched. The liquid crystal filter 12 is electrically connected to the control device 30, and is ON / OFF controlled by the control device 30. In the following description, unless otherwise specified, adjusting the predetermined polarization direction of the light passed through the liquid crystal filter 12 means switching the polarization direction between the first polarized light and the second polarized light which are orthogonal to each other. However, the predetermined polarization direction can be adjusted by controlling the voltage applied to the liquid crystal filter 12.

The liquid crystal filter 12 has a linear polarizing film 12a and a liquid crystal cell 12b. The linearly polarizing film 12a has linearly polarizing characteristics. The liquid crystal cell 12b is configured by filling a liquid crystal material between a pair of glass plates arranged so as to sandwich a separator. Alignment films whose orientation directions are orthogonal to each other are formed on the inner surfaces of the pair of glass plates.

In the liquid crystal filter 12, the polarizing axis PA2 of the linear polarizing film 12a and the polarizing axis PA1 of the film body 101 are orthogonal to each other so that the linear polarizing film 12a forms a cross Nicol with the optical film 100, that is, when viewed from the Z direction. It is arranged to do. Therefore, the direction of the polarization axis PA2 is a direction orthogonal to the paper surface. Therefore, in FIG. 2, the polarization axis PA2 is indicated by a black circle. The same applies to other drawings.

The liquid crystal filter 12 is arranged so that the linear polarizing film 12a is located on the light source 11 side between the light source 11 and the optical film 100. Therefore, when the unpolarized output light from the light source 11 is incident on the liquid crystal filter 12, only the second polarized light, which is the light having the polarization direction along the polarization axis PA2 of the linearly polarizing film 12a, forms the linearly polarizing film 12a. It passes through and enters the liquid crystal cell 12b.

When the liquid crystal filter 12 is in the OFF state, the second polarized light incident on the liquid crystal cell 12b is rotated by 90 ° in the polarization direction in the liquid crystal cell 12b, and as shown in the part (a) of FIG. 2, the first polarized light is polarized. It is output as light. That is, when the liquid crystal filter 12 is in the OFF state, apparently, the first polarized light selectively passes through the liquid crystal filter 12. On the other hand, when the liquid crystal filter 12 is in the ON state, a voltage is applied to the liquid crystal cell 12b. In this case, as shown in part (b) of FIG. 2, the second polarized light is output. That is, when the liquid crystal filter 12 is ON, the second polarized light selectively passes through the liquid crystal filter 12.

Therefore, the light irradiation unit 10A has a function of switching the inspection light L as the first polarized light and the inspection light L as the second polarized light to irradiate the optical film 100 by controlling the liquid crystal filter 12 ON / OFF. Has.

The arrangement relationship between the liquid crystal filter 12 and the optical film 100 shown in FIG. 2 corresponds to the arrangement relationship constituting the liquid crystal panel when the optical film 100 is attached to the liquid crystal cell 12b of the liquid crystal filter 12.

The imaging unit 20A has at least one camera 21 that images the optical film 100. FIG. 1 illustrates a form in which the imaging unit 20A has a plurality of cameras 21 arranged along the width direction of the optical film 100. The camera 21 is an area sensor camera such as a CCD camera. The camera 21 may be a line sensor camera. When the camera 21 is a line sensor camera, the inspection area A of the optical film 100 can be imaged by relatively moving the camera 21 and the optical film 100. The imaging unit 20A (specifically, the camera 21) is electrically connected to the control device 30, the imaging timing is controlled, and the obtained imaging data is input to the control device 30.

The control device 30 controls the light irradiation unit 10A and the image pickup unit 20A. In the first embodiment, the control device 30 describes the mode of controlling the liquid crystal filter 12 and the camera 21, but for example, the control device 30 may control the light output timing of the light source 11. The control device 30 has, for example, a computer (calculation unit). The control device 30 has a function of detecting a defective portion in the imaging data input from the imaging unit 20 and performing image processing such as highlighting the defective portion, and determines the defect position with respect to the image of the optical film 100. It may have a function of creating a defect map to be shown. As illustrated in FIG. 1, in the form in which the defect inspection system 1 includes the marking device 4, the control device 30 is electrically connected to the marking device 4 as shown in FIG. 1 to control the marking device 4. Then, the mark M based on the detected defect information may be added to the optical film 100.

Next, a method of inspecting the optical film 100 using the defect inspection device 3A will be described. When performing a defect inspection, the inspection light L in a predetermined polarization state (predetermined polarization direction) is irradiated from the light irradiation unit 10A to the inspection region A of the optical film 100 (inspection light irradiation step). When the optical film 100 is irradiated with the inspection light L in the inspection light irradiation step, the inspection region A is imaged by the imaging unit 20A (more specifically, the camera 21) (imaging step).

In the inspection light irradiation step, the liquid crystal filter 12 is controlled to be ON / OFF to switch a predetermined polarization state of the inspection light L. Specifically, for example, first, the liquid crystal filter 12 is set to the OFF state, and the optical film 100 is irradiated with the inspection light L, which is the first polarized light. After that, the liquid crystal filter 12 is set to the ON state, and the optical film 100 is irradiated with the inspection light L, which is the second polarized light. After setting the liquid crystal filter 12 in the ON state, it may be switched to the OFF state.

In the imaging step, the imaging unit 20A images the inspection region A in synchronization with the switching of the predetermined polarization state of the inspection light L.

In the above defect inspection method, when the optical film 100 is irradiated with the inspection light L which is the first polarized light in the inspection light irradiation step, the inspection light L and the optical film 100 are in a parallel Nicol state, that is, the polarization direction of the inspection light L. The inspection light L is incident on the optical film 100 in a state where the direction of the polarization axis PA1 of the film body 101 of the optical film 100 is substantially aligned with the optical film 100. On the other hand, when the optical film 100 is irradiated with the inspection light L which is the second polarized light in the inspection light irradiation step, the inspection light L and the optical film 100 are in a cross Nicol state, that is, the polarization direction of the inspection light L and the polarization axis PA1. The inspection light L is incident on the optical film 100 in a state where the light L is substantially orthogonal to the optical film 100.

Therefore, the inspection region A is imaged by the imaging unit 20A in synchronization with the switching of the predetermined polarization direction of the light to be passed through the liquid crystal filter 12, so that the inspection light L (parallel) in a parallel Nicol state with respect to the optical film 100. An inspection image when the optical film 100 is illuminated by each of the inspection light L (cross Nicol light) in the Nicole light) state and the cross Nicole state is obtained in the imaging step.

Next, a method for manufacturing the optical film 100 including a defect inspection method using the defect inspection apparatus 3A shown in FIGS. 1 and 2 will be described. Here, as shown in FIG. 2, a case where the optical film 100, which is a laminate of the protective film 102, the film main body 101, and the protective film 103, is manufactured will be described as an example.

When manufacturing the optical film 100, the protective film 102 is attached to one side of the film body 101 while conveying the strip-shaped film body 101, the strip-shaped protective film 102, and the strip-shaped protective film 103 in the longitudinal direction, respectively. The protective film 103 is bonded to the other side (bonding step). The film body 101, the protective film 102, and the protective film 103 can be bonded by using, for example, a pair of bonding rollers. In the bonding step, the protective film 102 and the protective film 103 may be bonded to the film body 101 at the same time, or one of the protective film 102 and the protective film 103 may be bonded to the film body 101 and then the other. You may.

After the bonding step, the defect inspection device carries the optical film 100 as a laminate of the protective film 103, the film body 101, and the protective film 102 between the light irradiation unit 10A and the image pickup unit 20A in the defect inspection device 3A. Defect inspection of the optical film 100 is performed at 3A (defect inspection step). In the defect inspection step, the defect inspection of the optical film 100 is performed by the defect inspection method described above. In the form in which the defect inspection system 1 includes the marking device 4, a step (marking step) of applying the mark M to the optical film 100 by the marking device 4 may be performed according to the result of the defect inspection step.

In the above manufacturing method, the optical film 100 as a laminate of the protective film 103, the film body 101, and the protective film 102 was inspected for defects by the defect inspection apparatus 3A. However, the film body 101 before the protective film 103 and the protective film 102 are bonded may be used as an optical film for defect inspection by the defect inspection apparatus 3A.

In the defect inspection method using the defect inspection device 3A and the defect inspection device 3A, by controlling the liquid crystal filter 12 ON / OFF, the inspection image of the optical film 100 by irradiation in the parallel Nicol state with one device and the cross Nicol An inspection image of the optical film 100 can be obtained by irradiation in the state.

Therefore, the defect inspection device 3A includes a transmission inspection optical system using parallel Nicol (hereinafter referred to as “normal transmission inspection optical system”) and a transmission inspection optical system using Cross Nicol (hereinafter referred to as “Cross Nicole transmission inspection optical system”). It has an integrated configuration. Defects may be detected only in either the normal transmission inspection optical system or the cross Nicol transmission inspection optical system, depending on the type. If the normal transmission inspection optical system and the cross Nicol transmission inspection optical system are integrated into one device as in the defect inspection device 3A, it is easy to reliably detect defects in the optical film 100.

Further, in the case of a defect that can be detected by either the normal transmission inspection optical system or the cross Nicol transmission inspection optical system, the defect that has appeared by, for example, the normal transmission inspection optical system does not appear in the inspection image of the Cross Nicol transmission inspection optical system. In this case, it can be determined that the defect is generated on the upper side (the image pickup unit 20A side) of the film main body 101. That is, it is also possible to identify the defect generation layer in the optical film 100. Therefore, in the method for manufacturing the optical film 100 having the above-mentioned defect inspection method, it is easier to manufacture the optical film 100 as a product containing no defects.

In the defect inspection device 3A, the defect inspection in the normal transmission inspection optical system and the defect inspection in the cross Nicol transmission inspection optical system can be switched by ON / OFF control of the liquid crystal filter 12. Since the liquid crystal filter 12 can be switched in a shorter time (for example, 0.1 msec to 25 msec), defect inspection with two inspection optical systems can be efficiently performed. Therefore, in the method for manufacturing the optical film 100 including the above-mentioned defect inspection method, the optical film 100 as a product containing no defects can be efficiently produced.

(Second Embodiment)
In the first embodiment, the light irradiation unit includes a liquid crystal filter (filter unit), and the liquid crystal filter is arranged under the optical film 100. However, in the defect inspection device, as shown in FIG. 3, the imaging unit may include a liquid crystal filter.

FIG. 3 is a schematic view of the defect inspection device 3B according to the second embodiment. The defect inspection device 3B includes a light irradiation unit 10B and an image pickup unit 20B. In FIG. 3, an example of an optical path of light is schematically shown by a dashed line arrow.

The light irradiation unit 10B is different from the light irradiation unit 10A of the first embodiment in that it does not have the liquid crystal filter 12. The configuration of the light source 11 included in the light irradiation unit 10B is the same as in the case of the first embodiment.

The imaging unit 20B differs from the imaging unit 20A of the first embodiment in that it has a liquid crystal filter 12 arranged between the camera 21 and the optical film 100. The configuration of the camera 21 is the same as that of the first embodiment. The camera 21 is electrically connected to the control device 30 and is controlled by the control device 30 as in the first embodiment.

The configuration of the liquid crystal filter 12 included in the image pickup unit 20B is the same as in the case of the first embodiment. The liquid crystal filter 12 is electrically connected to the control device 30, and is ON / OFF controlled by the control device 30.

The liquid crystal filter 12 is arranged so that the linear polarizing film 12a is located on the image pickup unit 20B side, and the polarizing axis PA2 of the linear polarizing film 12a and the polarizing axis PA1 of the film body 101 are in a cross-nicol state. In such an arrangement, light is incident on the liquid crystal filter 12 from the liquid crystal cell 12b side. Therefore, when the liquid crystal filter 12 is in the OFF state, the liquid crystal filter 12 selectively passes the first polarized light having a polarization direction orthogonal to the polarization axis PA2 of the linearly polarizing film 12a. However, the first polarized light incident on the liquid crystal filter 12 is rotated by 90 ° in the polarization direction while passing through the liquid crystal cell 12b, and is output as the second polarized light. On the other hand, when the liquid crystal filter 12 is in the ON state, the liquid crystal filter 12 selectively passes the second polarized light. When the liquid crystal filter 12 is in the ON state, the second polarized light incident on the liquid crystal filter 12 is output from the liquid crystal filter 12 while maintaining its polarization direction.

Next, a method of inspecting a defect of the optical film 100 by using the defect inspection device 3B will be described. When performing the defect inspection, the unpolarized output light from the light irradiation unit 10B is irradiated to the inspection region A of the optical film 100 as the inspection light L (inspection light irradiation step). When the optical film 100 is irradiated with the inspection light L in the inspection light irradiation step, the inspection region A is imaged by the imaging unit 20B (more specifically, the camera 21) (imaging step). More specifically, the camera 21 takes an image of the optical film 100 through the liquid crystal filter 12. In the imaging step, by imaging the optical film 100 with the camera 21 in synchronization with the ON / OFF control of the liquid crystal filter 12, an inspection image when the liquid crystal filter 12 is in the ON state is obtained, and the liquid crystal filter 12 is in the OFF state. Get the inspection image of the case.

The defect inspection device 3B is also a device in which the normal transmission inspection optical system and the cross Nicol inspection optical system are integrated as in the case of the first embodiment. This point will be described. For convenience of explanation, it is first assumed that the optical film 100 is free of defects.

In the inspection light irradiation step, the optical film 100 is irradiated with the inspection light L, which is unpolarized light. Since the film body 101 of the optical film 100 has a polarizing axis PA1, the first polarized light included in the inspection light L is output from the optical film 100 and incident on the liquid crystal filter 12.

When the liquid crystal filter 12 is in the OFF state, the first polarized light from the optical film 100 passes through the liquid crystal filter 12 as described above, is converted into the second polarized light in the passing process, and then is second polarized. It is output as light. The second polarized light output from the liquid crystal filter 12 is received by the camera 21. Therefore, when the liquid crystal filter 12 is in the OFF state, a transmitted image of the optical film 100 can be obtained. That is, when the liquid crystal filter 12 is set to the OFF state, the inspection optical system of the defect inspection device 3B functions as a normal transmission inspection optical system.

On the other hand, when the liquid crystal filter 12 is in the ON state, the liquid crystal filter 12 selectively passes the second polarized light as described above, so that the first polarized light from the optical film 100 passes through the liquid crystal filter 12. do not. In other words, the liquid crystal filter 12 in the ON state functions as a polarizing filter arranged in a cross Nicol state with respect to the optical film 100. That is, when the liquid crystal filter 12 is set to the ON state, the inspection optical system of the defect inspection device 3B functions as a cross transmission inspection optical system.

Therefore, the defect inspection device 3B is also a device in which the normal transmission inspection optical system and the cross Nicol inspection optical system are integrated.

When the defect inspection device 3B functions as a normal transmission inspection optical system, if the optical film 100 contains a defect, the defect may block the light or disturb the polarization state at the defect portion, resulting in an inspection image. In, the defective portion appears as, for example, a dark region.

On the other hand, when the defect inspection device 3B is made to function as a cross Nicol inspection optical system, if there is no defect on the upper side (image pickup unit 20B side) of the optical film 100 above the film body 101, as described above, the optical film 100 Since the first polarized light is output, the inspection image becomes a substantially pitch-black image. If a defect exists above the film body 101 (on the imaging unit 20B side) of the optical film 100, the polarization state of the first polarized light from the film body 101 is disturbed by the defect, so that the output from the optical film 100 is disturbed. The light includes second polarized light. Since the second polarized light can pass through the liquid crystal filter 12 in the ON state, the light is incident on the camera 21. Therefore, defects appear as bright spots in the inspection image.

The defect inspection device 3B is also a device in which the normal transmission inspection optical system and the cross Nicol inspection optical system are integrated, and the normal transmission inspection optical system and the cross Nicol inspection optical system are controlled by ON / OFF of the liquid crystal filter 12. Can be switched with. Therefore, the defect inspection device 3B also has the same function and effect as the defect inspection device 3A of the first embodiment.

Further, in the case of a defect that can be detected by either the normal transmission inspection optical system or the cross Nicol transmission inspection optical system, the defect that has appeared by, for example, the normal transmission inspection optical system does not appear in the inspection image of the Cross Nicol transmission inspection optical system. In this case, it can be determined that the defect is generated on the upper side (the image pickup unit 20A side) of the film main body 101. That is, the defect inspection device 3B can also identify the defect generation layer in the optical film 100.

The defect inspection device 3B can be applied to the defect inspection system 1 shown in FIG. 1 instead of the defect inspection device 3A. Therefore, the method for manufacturing the optical film 100 including the defect inspection method using the defect inspection apparatus 3B has the same effects as those in the first embodiment.

(Third Embodiment)
FIG. 4 is a schematic view of the defect inspection device 3C according to the third embodiment. Also in FIG. 4, the optical path of light is schematically shown by a alternate long and short dash line.

The defect inspection device 3C shown in FIG. 4 differs from the defect inspection device 3A of the first embodiment in that, in the first embodiment, the image pickup unit 20B described in the second embodiment is provided instead of the image pickup unit 20A. .. The liquid crystal filter 12 included in the light irradiation unit 10A, the liquid crystal filter 12 included in the imaging unit 20B, and the camera 21 are electrically connected to the control device 30 as in the first and second embodiments, and the control device 30 is used. Be controlled.

A method of inspecting a defect of the optical film 100 by using the defect inspection apparatus 3C will be described. When performing a defect inspection, the inspection light L is irradiated from the light irradiation unit 10A to the inspection region A (see FIG. 1) of the optical film 100 (inspection light irradiation step). When the optical film 100 is irradiated with the inspection light L in the inspection light irradiation step, the inspection region A is imaged by the imaging unit 20B (more specifically, the camera 21) (imaging step).

In the inspection light irradiation step, by controlling ON / OFF of the liquid crystal filter 12 included in the light irradiation unit 10A, the predetermined polarization state (predetermined polarization direction) of the inspection light L is switched as in the case of the first embodiment. .. In the imaging step, the liquid crystal filter 12 included in the imaging unit 20B is ON / OFF controlled according to the ON / OFF control of the liquid crystal filter 12 included in the light irradiation unit 10A, and the liquid crystal filters included in each of the light irradiation unit 10A and the imaging unit 20B are controlled. An inspection image is obtained according to the combination of the ON state and the OFF state of 12.

Specifically, when the liquid crystal filter 12 of the light irradiation unit 10A is set to the OFF state, the liquid crystal filter 12 of the image pickup unit 20B is controlled to be ON / OFF, and the liquid crystal filter 12 of the image pickup unit 20B is in the OFF state. Each inspection image is obtained when it is set to the ON state. Further, when the liquid crystal filter 12 of the light irradiation unit 10A is set to the ON state, the liquid crystal filter 12 of the image pickup unit 20B is controlled to be ON / OFF, and the liquid crystal filter 12 of the image pickup unit 20B is turned to the OFF state and the ON state. Each inspection image is obtained when it is set. Therefore, the defect inspection device 3C can obtain inspection images corresponding to the cases a to d shown in Table 1.

In case a, since the optical film 100 is irradiated with the inspection light L in the parallel Nicol state, the first polarized light is output from the optical film 100. The first polarized light can pass through the liquid crystal filter 12 in the case a as described in the second embodiment. Therefore, the inspection optical system in case a corresponds to the normal transmission inspection optical system.

In the case b, the first polarized light is output from the optical film 100 as in the case a. In case b, since the liquid crystal filter 12 of the imaging unit 20B is set to the ON state, when there are no defects in the optical film 100 (more specifically, when there are no defects above the film body 101), Light does not pass through the liquid crystal filter 12 included in the image pickup unit 20B. Therefore, the case b corresponds to the cross Nicol transmission inspection optical system.

In the case c and the case d, since the optical film 100 is irradiated with the inspection light L in the cross Nicol state, it corresponds to the cross Nicol transmission inspection optical system.

In this way, the defect inspection device 3C also integrates the normal transmission inspection optical system and the cross Nicol transmission inspection optical system, and the two optical systems can be switched by ON / OFF control of the liquid crystal filter 12. Therefore, the defect inspection device 3C and the defect inspection method using the defect inspection device 3C have the same effects as those of the defect inspection device 3A of the first embodiment.

The defect inspection device 3C can be applied to the defect inspection system 1 shown in FIG. 1 instead of the defect inspection device 3A. Therefore, the method for manufacturing the optical film 100 including the defect inspection method using the defect inspection apparatus 3B has the same effects as those in the first embodiment. In the defect inspection apparatus 3C, since the defect inspection of the optical film 100 can be performed in each of the four states of the cases a to d, it is easy to perform the inspection according to the optical film 100.

(Fourth Embodiment)
The defect inspection devices 3A, 3B, and 3C described in the first to third embodiments employ a transmission inspection optical system. However, as schematically shown in FIG. 5, the defect inspection apparatus may employ a reflection inspection optical system. FIG. 5 is a schematic view of the defect inspection device 3D according to the fourth embodiment. Also in FIG. 5, an example of the optical path of light is schematically shown by a alternate long and short dash line.

The defect inspection device 3D differs from the defect inspection device 3A of the first embodiment in that the light irradiation unit 10A and the image pickup unit 20A are arranged on the same side with respect to the optical film 100 to be inspected. .. In other words, in the defect inspection device 3D, when the inspection light L from the light irradiation unit 10A is reflected by the optical film 100 in the defect inspection device 3A of the first embodiment, the reflected light is reflected on the image pickup unit 20A. The light irradiation unit 10A and the imaging unit 20A are arranged so as to be incident. The configuration of the light irradiation unit 10A and the imaging unit 20A is the same as that of the first embodiment, and the defect inspection method of the optical film 100 using the defect inspection device 3D is the same as that of the first embodiment.

Since the defect inspection device 3D employs a reflection inspection optical system, the inspection light L (parallel Nicol light) in a parallel Nicol state with respect to the optical film 100 can be controlled by ON / OFF control of the liquid crystal filter 12. It is possible to obtain a reflection inspection image when the optical film 100 is irradiated with light and a reflection inspection image when the optical film 100 is irradiated with the inspection light L (cross Nicol light) in a cross-nicol state with respect to the optical film 100. Therefore, the defect inspection device 3D includes a reflection inspection optical system in a parallel Nicol state (hereinafter referred to as "normal reflection inspection optical system") and a reflection inspection optical system in a cross Nicol state (hereinafter referred to as a cross Nicol reflection inspection optical system). Are integrated into one. Further, the specular reflection inspection optical system and the cross Nicol reflection inspection optical system can be switched by controlling the liquid crystal filter 12 ON / OFF. Therefore, the defect inspection method of the optical film 100 using the defect inspection device 3D and the defect inspection device 3D has the same effect as that of the first embodiment.

The defect inspection device 3D employs a reflection inspection optical system as described above. When the inspection light L from the light irradiation unit 10A is the first polarized light, the inspection light L can propagate to the lower side of the film body 101 (the protective film 103 in FIG. 5). Therefore, in the specular reflection inspection optical system, defects contained below the film body 101 can also be detected. On the contrary, when the inspection light L from the light irradiation unit 10A is the second polarized light, the inspection light L cannot propagate below the film body 101. Therefore, in the cross Nicol reflection inspection optical system, defects located above the film body 101 and the film body 101 can be inspected, but defects below the film body 101 cannot be detected. Therefore, in the defect inspection apparatus 3D, the position of the defect in the thickness direction of the optical film 100 can be specified by switching between the inspection by the specular reflection inspection optical system and the inspection by the cross Nicol reflection inspection optical system.

Specifically, if a defect can be detected by inspection using each of the specular reflection inspection optical system and the cross Nicol reflection inspection optical system, the defect is located above the film body 101 and the film body 101. On the contrary, if the defect is detected in the specular reflection inspection optical system, but the defect is not detected in the cross Nicol reflection inspection optical system, the defect is located below the film body 101. In this way, the defect inspection device 3D can identify the position of the defect in more detail. An experiment (verification experiment) that verifies this point will be described. In the description of the verification experiment, the elements corresponding to the components in the above description will be described with the same reference numerals.

[Verification experiment]
The optical film 100 used in the verification experiment was a film in which the protective film 103, the film body 101, and the protective film 102 were laminated in this order. The material of the protective films 102 and 103 was TAC, and the material of the film body 101 was PVA. As the optical film 100 used in the verification experiment, a film in which air bubbles were mixed on the protective film 102 side was used.

In the verification experiment, the defect inspection device 3D having the configuration shown in FIG. 5 was used. However, a line sensor camera was adopted as the camera 21, and the line sensor camera and the optical film 100 were relatively moved to obtain an inspection image of the optical film 100.

(First inspection)
In the first inspection, the optical film 100 is set in the defect inspection device 3D so that the protective film 102 side is located on the light irradiation unit 10A side and the image pickup unit 20A side, and the liquid crystal filter 12 is set in the OFF state and the ON state. An inspection image of the optical film 100 was obtained by the normal reflection inspection optical system and the cross Nicol reflection inspection optical system. FIG. 6 shows an inspection image in the first inspection, the part (a) in FIG. 6 is an inspection image in the specular reflection inspection optical system, and the part (b) in FIG. 6 is a cross Nicol reflection inspection. It is an inspection image in an optical system.

(Second inspection)
In the second inspection, the optical film 100 was set in the defect inspection device 3D with the optical film 100 turned inside out as in the case of the first inspection. That is, the optical film 100 was set in the defect inspection device 3D so that the protective film 102 side was located on the side opposite to the light irradiation unit 10A and the image pickup unit 20A. Then, as in the case of the first inspection, an inspection image of the optical film 100 was obtained by the specular reflection inspection optical system and the cross Nicol reflection inspection optical system. FIG. 7 shows an inspection image in the second inspection, the part (a) in FIG. 7 is an inspection image in the specular reflection inspection optical system, and the part (b) in FIG. 7 is a cross Nicol reflection inspection. It is an inspection image in an optical system. In the parts (a) and (b) of FIG. 7, the regions indicated by the alternate long and short dash lines are regions corresponding to each other.

In the first inspection, bubble defects could be confirmed by both the inspection of the specular reflection inspection optical system and the inspection of the cross Nicol reflection inspection optical system. In this case, as described above, it is presumed that the defect is located above the film body 101. In the first inspection, the protective film 102 containing the bubble defect is located closer to the light irradiation unit 10A and the imaging unit 20A than the film body 101, so that the defect position with respect to the film body 101 matches that that can be determined from the inspection image. I can understand that.

In the second inspection, in the inspection with the specular reflection inspection optical system, bubble defects could be confirmed in the region surrounded by the alternate long and short dash line in part (a) of FIG. 7, while in the inspection with the cross Nicol reflection inspection optical system, FIG. No bubble defect could be confirmed in the region surrounded by the alternate long and short dash line in part (b) of 7. In this case, as described above, it is presumed that the defect is located below the film body 101. Then, in the second inspection, since the protective film 102 containing the bubble defect is located on the side opposite to the light irradiation unit 10A and the imaging unit 20A with respect to the film body 101, the defect position with respect to the film body 101 can be determined from the inspection image. It can be understood that it matches the one.

Therefore, in the defect inspection apparatus 3D, the position of the defect can be specified more concretely by comparing the results of the defect inspection in each of the specular reflection inspection optical system and the cross Nicol reflection inspection optical system.

The defect inspection device 3D can be applied to the defect inspection system 1 shown in FIG. 1 instead of the defect inspection device 3D. Therefore, the method for manufacturing the optical film 100 including the defect inspection method using the defect inspection apparatus 3D has the same effects as those in the first embodiment.

(Fifth Embodiment)
FIG. 8 is a schematic view of the defect inspection device 3E according to the fifth embodiment. The defect inspection device 3E is different from the defect inspection device 3A of the first embodiment in that it includes the first light irradiation unit 10A1 and the second light irradiation unit 10A2. Also in FIG. 8, an example of the optical path of light is schematically shown by a alternate long and short dash line.

The first light irradiation unit 10A1 is arranged on the side opposite to the image pickup unit 20A when viewed from the optical film 100, and the inspection light L is obliquely incident on the optical film 100. The configuration of the first light irradiation unit 10A1 is the same as the configuration of the light irradiation unit 10A of the first embodiment, except that the first light irradiation unit 10A1 is arranged so as to be obliquely incident in this way.

The second light irradiation unit 10A2 has the same configuration and arrangement as the light irradiation unit 10A described in the fourth embodiment. That is, the second light irradiation unit 10A2 is arranged with respect to the optical film 100 so as to form a reflection inspection optical system together with the image pickup unit 20A. In the second light irradiation unit 10A2, the light output from the optical film 100 based on the inspection light L from each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2 is the light receiving surface of the camera 21 included in the image pickup unit 20A. It may be arranged so as to be incident on the same region of the light, or it may be arranged so as to be incident on different regions.

The control device 30 is electrically connected to the liquid crystal filters 12 of the first light irradiation unit 10A1 and the second light irradiation unit 10A2, and the liquid crystal filters 12 of each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2. Is ON / OFF controlled.

Next, a defect inspection method for the optical film 100 using the defect inspection apparatus 3E will be described. First, the light output from the optical film 100 based on the inspection light L from each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2 is incident on the same region of the light receiving surface of the camera 21 included in the image pickup unit 20A. The form will be described.

When performing a defect inspection, the inspection light L is irradiated from the first light irradiation unit 10A1 to the inspection area A (see FIG. 1) of the optical film 100, and the inspection light L is emitted from the second light irradiation unit 10A2 to the optical film. Irradiate 100 inspection areas A (inspection light irradiation step). When the optical film 100 is irradiated with the inspection light L in the inspection light irradiation step, the optical film 100 is imaged by the imaging unit 20A (imaging step).

In the inspection light irradiation step, the inspection light L is irradiated from the first light irradiation unit 10A1 and the second light irradiation unit 10A2 to the inspection region A of the optical film 100 at different timings. Then, when the inspection light L is output from each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2, the light irradiation unit (first light irradiation unit 10A1 or second light irradiation unit 10A2) that outputs the inspection light L By controlling the liquid crystal filter 12 to be ON / OFF, the predetermined polarization state of the inspection light L is switched.

For example, when the inspection light L is output from the first light irradiation unit 10A1, the liquid crystal filter 12 included in the first light irradiation unit 10A1 is set to the OFF state, and the inspection light L which is the first polarized light is irradiated to the optical film 100. do. Subsequently, the liquid crystal filter 12 included in the first light irradiation unit 10A1 is set in the ON state, and the optical film 100 is irradiated with the inspection light L which is the second polarized light. When the inspection light L is output from the second light irradiation unit 10A2, the liquid crystal filter 12 included in the second light irradiation unit 10A2 is ON / OFF controlled as in the case of the first light irradiation unit 10A1.

In the imaging step, the inspection region A of the optical film 100 is imaged by the camera 21 of the imaging unit 20A in synchronization with the ON / OFF control of the liquid crystal filter 12 when the inspection light L is output from the first light irradiation unit 10A1. Similarly, the inspection region A of the optical film 100 is imaged by the camera 21 of the imaging unit 20A in synchronization with the ON / OFF control of the liquid crystal filter 12 when the inspection light L is output from the second light irradiation unit 10A2.

When the light output from the optical film 100 based on the inspection light L from each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2 is incident on different regions of the light receiving surface of the camera 21 included in the image pickup unit 20A. The defect inspection method will be described. This case also has the inspection light irradiation step and the imaging step.

However, in the inspection light irradiation step, the inspection light L may be output from the first light irradiation unit 10A1 and the second light irradiation unit 10A2 at the same timing. Then, the liquid crystal filter 12 of each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2 is ON / OFF controlled. The timing of the ON / OFF control of the liquid crystal filter 12 included in the first light irradiation unit 10A1 and the ON / OFF control of the liquid crystal filter 12 included in the second light irradiation unit 10A2 may be the same or different.

In the imaging step, the inspection region A of the optical film 100 is imaged by the camera 21 of the imaging unit 20A in synchronization with the ON / OFF control timing of the liquid crystal filter 12 of each of the first light irradiation unit 10A1 and the second light irradiation unit 10A2. do.

In the defect inspection device 3E, the first light irradiation unit 10A1 and the imaging unit 20A constitute the transmission inspection optical system described in the first embodiment. Therefore, in the defect inspection device 3E and the defect inspection device 3E, the defect inspection using the first light irradiation unit 10A1 has the same function and effect as the defect inspection device 3A described in the first embodiment.

In the defect inspection device 3E, the second light irradiation unit 10A2 and the imaging unit 20A constitute the reflection inspection optical system described in the fourth embodiment. Therefore, in the defect inspection device 3E and the defect inspection device 3E, the defect inspection using the second light irradiation unit 10A2 has the same function and effect as the defect inspection device 3E described in the fourth embodiment.

Further, the defect inspection device 3E is a device in which the transmission inspection optical system and the reflection inspection optical system are integrated. Therefore, a defect that can be detected by the transmission inspection optical system and a defect that can be detected by the reflection inspection optical system can be detected by one device, and the defect of the optical film 100 can be detected more reliably.

The defect inspection device 3E can be applied to the defect inspection system 1 shown in FIG. 1 instead of the defect inspection device 3A. Therefore, the method for manufacturing the optical film 100 including the defect inspection method using the defect inspection apparatus 3E has the same effects as those in the first embodiment.

(Sixth Embodiment)
FIG. 9 is a schematic view of the defect inspection device 3F according to the sixth embodiment. The defect inspection device 3F is different from the defect inspection device 3A of the first embodiment in that the light irradiation unit 10C is provided instead of the light irradiation unit 10A. Also in FIG. 9, the optical path of light is schematically shown by a alternate long and short dash line.

The light irradiation unit 10C includes a light source 11, a polarizing separation element 13, an optical path synthesis unit 14, a first mirror 15A, a second mirror 15B, a linear polarizing film 16, and a liquid crystal filter 12. The configuration of the light source 11 and the configuration of the liquid crystal filter 12 are the same as those of the first embodiment.

The polarization separating element 13 is arranged on the optical path of the output light from the light source 11, and separates the unpolarized output light from the light source 11 into first polarized light and second polarized light whose polarization directions are orthogonal to each other. do. Specifically, it transmits the second polarized light and reflects the first polarized light. An example of the polarization separating element 13 is an element using APF (Advanced Polarizing Film), for example, an element in which APF is formed on one side surface of a prism, a glass plate, or the like.

The optical path synthesizing unit 14 is arranged on the optical path of the second polarized light. Specifically, it is arranged between the polarizing separation element 13 and the optical film 100 in the Z direction. The optical path synthesizing unit 14 is an optical element that synthesizes the optical path of the first polarized light separated by the polarization separating element 13 into the optical path of the second polarized light and outputs the optical path. The optical path synthesizing unit 14 outputs the first polarized light and the second polarized light to the optical film 100 side in a state where the optical paths of the first polarized light and the second polarized light are matched. The example of the optical path synthesizing unit 14 is the same as that of the polarization separating element 13.

The first mirror 15A and the second mirror 15B form an optical system that guides the first polarized light separated by the polarization separating element 13 to the optical path synthesizer 14. Specifically, the first mirror 15A is arranged on the side of the polarizing separation element 13, and reflects the first polarized light from the polarization separation element 13 toward the optical film 100. The second mirror 15B is on the optical path of the first polarized light reflected by the first mirror 15A, is arranged on the side of the optical path synthesizer 14, and is the first polarized light reflected by the first mirror 15A. Is reflected toward the optical path synthesizer 14 side.

The linearly polarizing film 16 is an optical film having linearly polarizing characteristics. The linearly polarizing film 16 is arranged on the optical path of the second polarized light between the polarizing separation element 13 and the optical path synthesizing unit 14. In the linearly polarizing film 16, the polarizing axis PA1 of the film body 101 and the polarizing axis PA3 of the linear polarizing film 16 are arranged so that the polarizing axis PA3 is in a cross-nicol state with the optical film 100, that is, when viewed from the Z direction. They are arranged so as to be orthogonal to each other.

The liquid crystal filter 12 is arranged on the optical path of the first polarized light between the first mirror 15A and the second mirror 15B. In the liquid crystal filter 12, the linearly polarizing film 12a is located on the second mirror 15B side, and the polarizing axis PA2 of the linearly polarizing film 12a is arranged so as to be in a parallel Nicol state with the optical film 100. In such an arrangement, when the liquid crystal filter 12 is ON, the liquid crystal filter 12 passes the first polarized light. On the other hand, when the liquid crystal filter 12 is in the OFF state, the liquid crystal filter 12 blocks the first polarized light.

In the configuration of the light irradiation unit 10C, the output light from the light source 11 is separated into a second polarized light and a first polarized light by the polarization separating element 13. Specifically, the second polarized light passes through the polarization separating element 13, and the first polarized light is reflected toward the first mirror 15A.

The second polarized light transmitted through the polarization separating element 13 is incident on the linear polarizing film 16. Since the direction of the polarization axis PA3 of the linearly polarizing film 16 is the same as the polarization direction of the second polarized light, the second polarized light from the polarization separating element 13 passes through the linearly polarizing film 16 and the optical path synthesizer 14 Is incident on.

On the other hand, the first polarized light reflected by the polarization separating element 13 is reflected by the first mirror 15A toward the second mirror 15B. Since the liquid crystal filter 12 is arranged between the first mirror 15A and the second mirror 15B, the first polarized light reflected by the first mirror 15A is incident on the liquid crystal filter 12.

When the liquid crystal filter 12 is in the ON state, the first polarized light passes through the liquid crystal filter 12. The first polarized light transmitted through the liquid crystal filter 12 is reflected by the second mirror 15B and is incident on the optical path synthesizing unit 14.

The optical path synthesizing unit 14 outputs the second polarized light that has passed through the linearly polarizing film 16 in accordance with the optical path of the first polarized light from the second mirror 15B. In other words, the optical path synthesizer 14 synthesizes the second polarized light and the first polarized light and outputs the light as unpolarized light. Therefore, when the liquid crystal filter 12 is ON, the light irradiation unit 10C outputs unpolarized inspection light L.

When the liquid crystal filter 12 is in the OFF state, the first polarized light is blocked by the liquid crystal filter 12, so that the first polarized light does not reach the optical path synthesis unit 14. Therefore, only the second polarized light that has passed through the linearly polarizing film 16 is output from the optical path synthesizing unit 14. That is, when the liquid crystal filter 12 is in the OFF state, the light irradiation unit 10C outputs the inspection light L which is the second polarized light.

In this way, the light irradiation unit 10C can switch between the unpolarized inspection light L and the second polarized light inspection light L by controlling the liquid crystal filter 12 to be ON / OFF.

Since the light irradiation unit 10C can switch and output the polarization state of the inspection light L by ON / OFF control of the liquid crystal filter 12, the defect inspection method of the optical film 100 using the defect inspection device 3F is the case of the defect inspection device 3A. Is similar to.

When the inspection light L is in an unpolarized state, the inspection light L includes the first polarized light. Therefore, in the sixth embodiment, when the liquid crystal filter 12 is in the ON state, the optical film 100 is irradiated with the inspection light L, which is parallel Nicol light. On the other hand, when the liquid crystal filter 12 is in the OFF state and the inspection light L is the second polarized light, the optical film 100 is irradiated with the inspection light L which is the cross Nicol light. Therefore, in the defect inspection device 3F, the normal transmission inspection optical system and the cross Nicol inspection optical system are integrated, and the inspection optical systems are switched by the ON / OFF control of the liquid crystal filter 12. Therefore, the defect inspection device 3F and the defect inspection method of the optical film using the defect inspection device 3F have the same effects as those in the case of the first embodiment.

When light passes through the liquid crystal filter 12, the amount of light is attenuated as compared with the case where light passes through, for example, a polarizing film. However, when the defect inspection device 3F is used as the cross Nicol transmission inspection optical system to perform the defect inspection, the second polarized light does not pass through the liquid crystal filter 12, so that the optical film is used in the inspection of the cross Nicol transmission inspection optical system. It is easy to secure the amount of light required for 100 illuminations. When the defect inspection device 3F is used as the normal transmission inspection optical system to perform the defect inspection, the first polarized light passes through the liquid crystal filter 12. In this case, as described above, the amount of light is attenuated. However, in the case of normal transmission, it is easier to secure the amount of light required for illuminating the optical film 100 than in the case of cross Nicol transmission. Therefore, the influence of the attenuation of the amount of light is small. Depending on the configuration of the liquid crystal filter 12, the amount of light passing through the linear polarizing film 12a can be adjusted by adjusting the voltage applied to the liquid crystal filter 12. As a result, in the defect inspection device 3F using the liquid crystal filter 12, it is possible to reduce the amount of increase in the amount of light from the light source 11 in order to obtain the amount of light required for the defect inspection. Contribute to.

The defect inspection device 3F can be applied to the defect inspection system 1 shown in FIG. 1 instead of the defect inspection device 3A. Therefore, the method for manufacturing the optical film 100 including the defect inspection method using the defect inspection apparatus 3F has the same effects as those in the first embodiment.

In the sixth embodiment, the light irradiation unit 10C comprises a light source 11, a polarizing separation element 13, an optical path synthesis unit 14, a first mirror 15A, a second mirror 15B, a linear polarizing film 16, and a liquid crystal filter 12. The case of having was described. However, the light irradiation unit 10C may include a light source 11, a polarizing separation element 13, an optical path synthesis unit 14, a first mirror 15A, a second mirror 15B, and a liquid crystal filter 12. That is, the light irradiation unit 10C does not have to have the linear polarizing film 16. In the embodiment in which the light irradiation unit 10C has the linearly polarizing film 16, the accuracy of the polarization direction of the light passing through the linearly polarizing film 16 is improved. Therefore, the inspection can be performed in a more accurate cross-nicol state.

(7th Embodiment)
FIG. 10 is a schematic view of the defect inspection device 3G according to the seventh embodiment. The defect inspection device 3G is different from the sixth embodiment in that the light irradiation unit 10C is arranged on the same side as the image pickup unit 20A as viewed from the optical film 100 so as to form a reflection inspection optical system together with the image pickup unit 20A. It's different. Since the same as the sixth embodiment except for this difference, the operation and effect of the defect inspection device 3G and the defect inspection method using the defect inspection device 3G are also the same as those of the sixth embodiment. Also in FIG. 10, an example of the optical path of light is schematically shown by a alternate long and short dash line.

The configuration of the defect inspection device 3G corresponds to the configuration in which the light irradiation unit 10A is replaced with the light irradiation unit 10C in the defect inspection device 3D of the fourth embodiment. Therefore, the defect inspection device 3G and the defect inspection method using the defect inspection device 3G have the same effects as those of the reflection inspection optical system described in the fourth embodiment.

In the seventh embodiment as well, as in the case of the sixth embodiment, the light irradiation unit 10C does not have to have the linearly polarizing film 16. The action and effect when the light irradiation unit 10C has the linearly polarizing film 16 is the same as in the case of the sixth embodiment.

In the sixth and seventh embodiments, in order to improve the polarization direction accuracy of the two polarized lights separated by the polarizing separation element 13, the polarization separation element 13 and the liquid crystal filter 12, preferably the first mirror 15A to the liquid crystal filter 12 A linearly polarizing film in a state of being parallel to the first polarized light may be further installed between the two.

(8th Embodiment)
FIG. 11 is a schematic view of the defect inspection device 3H according to the eighth embodiment. The defect inspection device 3H differs from the defect inspection device 3F of the sixth embodiment in that the light irradiation unit 10D is provided instead of the light irradiation unit 10C. Also in FIG. 11, an example of the optical path of light is schematically shown by a alternate long and short dash line.

The light irradiation unit 10D includes a light source 11, an optical path synthesis unit 14, a linear polarizing film 16, a light source 17, and a liquid crystal filter 12A. The configuration of the light source 11, the optical path synthesizer 14, and the linear polarizing film 16 is the same as that of the sixth embodiment. Further, the arrangement relationship of the light source 11, the linearly polarizing film 16 and the optical path synthesizing unit 14 is the same as that of the sixth embodiment except that the polarization separating element 13 is not arranged between the light source 11 and the linearly polarizing film 16. Is.

The light source 17 is arranged on the side of the optical path synthesizing unit 14 (side along the Y direction). A liquid crystal filter 12A is arranged between the light source 17 and the optical path synthesis unit 14. The liquid crystal filter 12A functions as a shutter that switches between a case where the first deflection light is passed and a case where the light is blocked by switching ON / OFF. The liquid crystal filter 12A includes the light source 17 and the liquid crystal filter 12A. When the first polarized light output from the liquid crystal filter 12A is incident on the optical path synthesizer 14, it passes through the linear polarizing film 16 and is incident on the optical path synthesizer 14. It is arranged so as to be combined with the optical path of the second polarized light.

For example, as shown in FIG. 11, the liquid crystal filter 12A includes a liquid crystal cell 12b, a linear polarizing film 12a provided on one surface of the liquid crystal cell 12b, and the other surface of the liquid crystal cell 12b (linear polarizing film 12a). A linearly polarizing film 12c is provided on a surface opposite to the surface provided. The polarizing axis PA2 of the linear polarizing film 12a and the polarizing axis PA5 of the linear polarizing film 12c are orthogonal to each other. The liquid crystal filter 12A is arranged so that the linear polarizing film 12c faces the light source 17 and the polarizing axis PA2 is in a parallel Nicol state with the polarizing axis PA1. In such a configuration and arrangement of the liquid crystal filter 12A, when the liquid crystal filter 12A is in the OFF state, the first polarized light among the light (unpolarized light) from the light source 17 selectively passes through the liquid crystal filter 12A, and the liquid crystal filter 12A Is ON, the light from the light source 17 is blocked.

The light irradiation unit 10D has the same function as the light irradiation unit 10C by controlling the liquid crystal filter 12A ON / OFF while the light is output from the light source 11 and the light source 17, respectively. Therefore, the defect inspection method of the optical film 100 using the defect inspection device 3H and the defect inspection device 3H has the same effect as that of the sixth embodiment.

In the defect inspection device 3H, the cross Nicol transmission inspection optical system can also be realized by turning off the light source 17, that is, by stopping the output of light from the light source 17.

The defect inspection device 3H employs a transmission inspection optical system, but even if the light irradiation unit 10D is arranged on the same side as the image pickup unit 20A and the reflection inspection optical system is adopted as in the seventh embodiment. good.

(9th Embodiment)
In the first to eighth embodiments, the defect inspection apparatus for inspecting an optical film having linearly polarized light characteristics has been described. However, the optical film does not have to have linearly polarized light characteristics. As a ninth embodiment, a defect inspection apparatus when an optical film having no linear polarization characteristic is an inspection target will be described. FIG. 12 is a schematic view of the defect inspection device 3I according to the ninth embodiment.

The defect inspection device 3I is a device that inspects defects in the optical film 100A that does not have linearly polarized light characteristics. Examples of the optical film 100A include the protective film 102, the protective film 103, and the retardation film shown in FIG.

The defect inspection device 3I is different from the defect inspection device 3A of the first embodiment in that the linear polarizing film (first linear polarizing film) 40 is provided. The defect inspection device 3I will be described focusing on this difference.

The linearly polarizing film 40 is a film having linearly polarizing characteristics and has a polarizing axis PA4. The linearly polarizing film 40 is arranged between the optical film 100A and the imaging unit 20A so as to form a cross Nicol with the linearly polarizing film 12a of the liquid crystal filter 12. In FIG. 12, the linearly polarizing film 40 is arranged so that the Y direction coincides with the direction of the polarizing axis PA4.

A method of inspecting a defect of the optical film 100A by using the defect inspection apparatus 3I will be described. When performing a defect inspection, the inspection light L in a predetermined polarized state is irradiated from the light irradiation unit 10A to the inspection region of the optical film 100A (inspection light irradiation step). When the optical film 100A is irradiated with the inspection light L in the inspection light irradiation step, the inspection region is imaged by the imaging unit 20A (more specifically, the camera 21) (imaging step).

In the inspection light irradiation step, as in the case of the first embodiment, the liquid crystal filter 12 is ON / OFF controlled to switch the predetermined polarization state of the inspection light L. In the imaging step, the imaging unit 20A images the inspection region of the optical film 100A in synchronization with the switching of the predetermined polarization state of the inspection light L.

Since the optical film 100A does not have linearly polarized light, both the first polarized light and the second polarized light pass through the optical film 100A. A linearly polarizing film 40 is arranged between the optical film 100A and the imaging unit 20A, the first polarized light passes through the linearly polarizing film 40, and the second polarized light is blocked by the linearly polarizing film 40.

Therefore, also in the defect inspection device 3I, the normal transmission inspection optical system and the cross Nicol transmission inspection optical system are integrated, and the switching of these inspection optical systems is performed by ON / OFF control of the liquid crystal filter 12. Therefore, the defect inspection device 3I and the defect inspection method using the defect inspection device 3I have the same effects as those in the case of the first embodiment.

The defect inspection device 3I can be applied instead of the defect inspection device 3A of the defect inspection system 1 of FIG. 1 when the inspection target transported by the transport unit 2 in FIG. 1 is the optical film 100A. The method for producing an optical film including the defect inspection apparatus 3I and the defect inspection method using the defect inspection apparatus 3I has the same effects as those in the case of the first embodiment.

The defect inspection method of the optical film 100A using the defect inspection device 3I and the defect inspection device 3I may be applied to the case of manufacturing the optical film 100A itself, and for example, in the process of manufacturing the optical film 100, the film main body. It may be used for defect inspection of the protective film 102 and the protective film 103 which are transported before being bonded to 101.

The defect inspection device 3I has been described as a modification of the defect inspection device 3A. However, even in the configuration of the defect inspection apparatus described as the second embodiment and the fourth to eighth embodiments, as described in the ninth embodiment, the linearly polarizing film 40 is further provided to have linear polarization characteristics. It is possible to carry out a defect inspection of the optical film 100A. Specifically, as described in the fourth to seventh embodiments, when the light irradiation unit has the liquid crystal filter 12, a linearly polarizing film is formed between the optical film 100A having no linear polarization characteristic and the imaging unit. As described in the ninth embodiment, the 40 may be arranged so as to form a cross Nicol with the linearly polarizing film 12a of the liquid crystal filter 12. As described in the eighth embodiment, when the light irradiation unit includes the linearly polarizing film 16 and the liquid crystal filter 12A, the linearly polarizing film 40 is inserted between the optical film 100A having no linearly polarized light characteristics and the imaging unit. , It may be arranged so as to form a cross Nicol with the linear polarizing film 16. When the defect inspection apparatus of the sixth to eighth embodiments includes the linear polarizing film 40 for performing the defect inspection of the optical film 100A, the linear polarizing film 40 corresponds to the first linear polarizing film and is linear. The polarizing film 16 corresponds to the second linear polarizing film.

As described in the second embodiment, when the imaging unit has the liquid crystal filter 12, a linearly polarizing film 40 is inserted between the optical film and the light irradiation unit, as described in the ninth embodiment, the liquid crystal filter. It may be arranged so as to form a cross Nicol with the linearly polarizing film 12a of 12.

As described in the third embodiment, when both the light irradiation unit and the imaging unit have a liquid crystal filter, a defect inspection of the optical film 100A is performed by combining ON / OFF control of the liquid crystal filters of the light irradiation unit and the imaging unit. Is possible.

An optical film has been exemplified as a film having no polarization characteristics, but an example of a film having no polarization characteristics may be a separator film for a battery or the like.

The various embodiments of the present invention have been described above. However, the present invention is not limited to the various embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

In the various embodiments illustrated, one control device controls the liquid crystal filter and the camera, but separate control devices may be provided for the liquid crystal filter and the camera. In the various embodiments described above, the form in which the defect inspection device includes the control device has been mainly described, but the defect inspection device may be a component different from the defect inspection device. For example, it may be a component of a defect inspection system, or it may be an apparatus appropriately prepared by a user of the defect inspection apparatus.

The filter unit is not limited to the liquid crystal filter as long as it is configured so that the polarization direction of the light to be passed can be switched.

When the inspection target is a film having linear polarization characteristics, the film and the liquid crystal filter are arranged so that the predetermined polarization direction of the light passing through the filter unit and the polarization axis of the film are in a parallel Nicol state or a cross Nicol state. The form in which is arranged has been described. However, depending on the inspection target, the filter unit and the film may be arranged so that the predetermined polarization direction of the light passing through the filter unit and the polarization axis of the film are in a half-cross Nicol state. Alternatively, when the filter unit is a liquid crystal filter, the voltage applied to the liquid crystal filter is adjusted so that the predetermined polarization direction of the light passing through the filter unit and the polarization axis of the film are in a half-cross Nicol state. An inspection may be performed. When the inspection target is a film having no linearly polarized light characteristics, the arrangement relationship between the filter unit and the paired linearly polarized light film may be in a half-cross Nicol state as described above. When the inspection target is a film having no linear polarization characteristic and the filter unit is a liquid crystal filter, the polarization of the linearly polarizing film paired with the filter unit and the predetermined polarization direction of the light passing through the filter unit. The inspection may be performed by adjusting the voltage applied to the liquid crystal filter so that the relationship with the shaft is in a half-crossed Nicol state.

The various embodiments illustrated so far may be combined with each other as appropriate. For example, the light irradiation unit described in one embodiment may be replaced with the light irradiation unit of another embodiment, or the imaging unit described in one embodiment may be replaced with the imaging unit of another embodiment. ..

3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I ... Defect inspection device, 10A, 10A1, 10A2, 10B, 10C, 10D ... Light irradiation unit, 11 ... Light source, 12 ... Liquid crystal filter, 13 ... Polarized light Separation element, 14 ... Optical path synthesizer, 15A ... 1st mirror (optical system), 15B ... 2nd mirror (optical system), 16 ... Linearly polarizing film, 20A, 20B ... Imaging unit, 21 ... Camera, 40 ... Linearly polarized light Film (first linear polarizing film), 100, 100 A ... Optical film (film), A ... Inspection area, L ... Inspection light.

Claims (5)

A film defect inspection device
A light irradiation unit that outputs inspection light to irradiate the inspection area of the film, and a light irradiation unit.
An imaging unit that captures the inspection area and
With
The film is an optical film having linearly polarized light characteristics.
The light irradiation unit is
Light source and
A polarization separating element that separates the light from the light source into first polarized light and second polarized light whose polarization directions are orthogonal to each other.
Optical path synthesis that is arranged on the optical path of the second polarized light separated by the polarization separating element and synthesizes the optical path of the first polarized light separated by the polarization separating element into the optical path of the second polarized light. Department and
An optical system that guides the monopolarized light separated by the polarization separating element to the optical path synthesizer, and
A filter unit for the Ru is disposed on the optical path of the first polarized light guided by the optical system,
Have,
The film is arranged on the optical path of the second polarized light.
The filter unit can be switched between a case where the first polarized light is selectively passed and a case where the first polarized light is blocked.
Defect inspection equipment. The filter unit has a liquid crystal filter configured by providing a linear polarizing film on one side of the liquid crystal cell.
The defect inspection apparatus according to claim 1. The light irradiation unit is arranged between the polarization separating element and the optical path synthesis unit on the optical path of the second polarized light, is arranged in a cross-nicol state with respect to the film, and is the second polarized light. Has a polarizing film that allows light to pass through,
The defect inspection apparatus according to claim 1 or 2. A film defect inspection device
A light irradiation unit that outputs inspection light to irradiate the inspection area of the film, and a light irradiation unit.
An imaging unit that captures the inspection area and
With
Further having a first linear polarizing film arranged between the imaging unit and the film,
The film is a film having no polarization characteristics and has no polarization characteristics.
The light irradiation unit is
Light source and
A polarization separating element that separates the light from the light source into first polarized light and second polarized light whose polarization directions are orthogonal to each other.
An optical path synthesizer arranged on the optical path of the second polarized light and synthesizing the optical path of the first polarized light into the optical path of the second polarized light.
An optical system that guides the first polarized light separated by the polarization separating element to the optical path synthesizer, and
On the optical path of the second polarized light, it is arranged between the polarization separating element and the optical path synthesizer, and is arranged in a cross-nicol state with respect to the first linear polarizing film, and the second polarized light is transmitted. The second linear polarizing film to be passed through,
A filter unit for the Ru is disposed on the optical path of the first polarized light guided by the optical system,
Have,
The film is arranged on the optical path of the second polarized light.
The filter unit can be switched between a case where the first polarized light is selectively passed and a case where the first polarized light is blocked.
Defect inspection equipment. It has two light irradiation units.
The first light irradiation unit, which is one of the two light irradiation units, is arranged on the side opposite to the image pickup unit when viewed from the film.
The second light irradiation unit, which is the other of the two light irradiation units, is arranged on the same side as the image pickup unit when viewed from the film.
The defect inspection apparatus according to any one of claims 1 to 4.

Images