The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 30, 2024
Filed:
Oct. 21, 2021
Dai Nippon Printing Co., Ltd., Tokyo, JP;
Shosei Kubota, Kashiwa, JP;
Hikaru Hotta, Tsukuba, JP;
Yoshiko Tanaka, Tokorozawa, JP;
Takashi Kuroda, Moriya, JP;
Akinobu Ushiyama, Moriya, JP;
DAI NIPPON PRINTING CO., LTD., Tokyo, JP;
Abstract
Provided is an optical film that can eliminate rainbow unevenness when viewed with the naked eyes and provide favorable color tone uniformity when viewed at an oblique angle. This optical film has a low-refractive index layer on a plastic film, the plastic film has a slow axis that is an axis with the largest refractive index in a plane, and a fast axis that is an axis orthogonal to the slow axis in the plane of the plastic film, and the low-refractive index layer is located on the surface of the optical film. Linearly polarized light is incident, under predetermined conditions, from a surface on a side opposite to the low-refractive index layer of the optical film, and transmitted light of the linearly polarized light is used to measure the a* value and b* value of the L*a*b* color system at 11 measurement points with different angles. The measurements at the 11 measurement points are used to calculate a sum of square of a difference in a* between adjacent measurement points and square of a difference in b* between the adjacent measurement points. The sum was calculated for each of 10 adjacent points. The optical film has a Σ, which indicates a total of the above sums, within a predetermined range.