公开(公告)号：US20230311559A1

公开(公告)日：2023-10-05

申请号：US18127345

申请日：2023-03-28

Applicant: NITTO DENKO CORPORATION

Inventor： Saori YAMAMOTO ,  Masahiro YAEGASHI ,  Yuji TOYOTA

IPC: B43L1/10 ,  B32B18/00 ,  B32B7/023

CPC classification number: B43L1/10 ,  B32B18/00 ,  B32B7/023 ,  B43K5/02

Abstract: A writing board set includes a writing board and a writing utensil containing ink. The writing board reflects back, when unpolarized light is incident on its surface at a viewer's side, polarized light which is parallel to a first direction and which has a degree of polarization of 95% or more. Ld*, ad*, and bd* are values of L*, a*, and b* as obtained by irradiating the surface of the writing board with light that has been transmitted through a polarizing layer having a transmission axis which is orthogonal to the first direction, and measuring total reflectance through spectrophotometry. Li*, ai*, and bi* are values of L*, a*, and b* as obtained by irradiating the ink having been introduced onto a surface of a glass panel with unpolarized light, and measuring total reflectance through spectrophotometry. A color difference ΔE*ab as defined by eq. (1) is 19 or less:


ΔE*ab[(Li*−Ld*)2+(ai*−ad*)2+(bi*−bd*)2]1/2  (1).