Abstract: A defect detection method of a layered film having a polarizing plate and an optical compensation layer includes steps of: applying light from a light source arranged at the polarizing plate layer side of the film surface of the layered film; a step of imaging a transmitting light image of the layered film by an imaging unit arranged at the optical compensation layer side of the film surface; and a defect detection step for detecting a defect existing on the layered film according to the transmitting light image captured by the imaging unit. The imaging unit performs imaging via an inspection polarizing filter arranged on the optical path between the light source and the imaging unit and adjacent to the imaging unit; and an inspection phase difference filter arranged on the optical path between the light source and the imaging unit and between the inspection polarizing filter and the layered film.

Abstract: Provided are a layered film defect detection device capable of performing defect detection considering irregularities of optical performance of a phase difference layer constituting the layered film without requiring insertion of a new part into an optical path; and a layered film defect detection method. A defect detection device used for a layered film (11) having a polarizing plate (1) and a phase difference layer (separator (2)) includes: a light source (12) arranged at one side of the film surfaces of the layered film (11), an imaging unit (13) arranged on the other side of the film surface; an inspection polarization filter (15) arranged between the light source (12) and the imaging unit (13); a defect detection unit (14b) for detecting a defect existing on the polarizing plate (1) according to the captured image; and an optical axis adjusting unit (16) for adjusting a relative angle position of the polarization axis (L2) of a polarizing filter (15) and a polarization axis (L1) of a polarizer (2).

Abstract: When inspecting a defect of a layered film having a polarizer by using an inspection polarizing filter or an inspection phase difference filter, members to be arranged in the imaging optical path are arranged in an appropriate order. A defect detection method of a layered film (11) having a polarizing plate (1) and an optical compensation layer includes: a step of applying light from a light source arranged at the polarizing plate layer side of the film surface of the layered film (11); a step of imaging a transmitting light image of the layered film (11) by an imaging unit (12) arranged at the optical compensation layer side of the film surface; and a defect detection step for detecting a defect existing on the layered film (11) according to the transmitting light image captured by the imaging unit (12).

Abstract: Provided are a layered film defect detection device capable of performing defect detection considering irregularities of optical performance of a phase difference layer constituting the layered film without requiring insertion of a new part into an optical path; and a layered film defect detection method. A defect detection device used for a layered film (11) having a polarizing plate (1) and a phase difference layer (separator (2)) includes: a light source (12) arranged at one side of the film surfaces of the layered film (11), an imaging unit (13) arranged on the other side of the film surface; an inspection polarization filter (15) arranged between the light source (12) and the imaging unit (13); a defect detection unit (14b) for detecting a defect existing on the polarizing plate (1) according to the captured image; and an optical axis adjusting unit (16) for adjusting a relative angle position of the polarization axis (L2) of a polarizing filter (15) and a polarization axis (L1) of a polarizer (2).