| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical filter for an image display device having a sufficient persistence of the absorption effect for near IR rays. SOLUTION: The optical filter contains a salt compound consisting of cations and quencher anions selected from the compounds expressed by formulae (I) to (III). In the formulae, each of a ring A and a ring A' represents a benzene ring, naphthalene ring or pyridine ring, each of R1 and R1 ' represents a halogen atom, nitro group, cyano group, 6-30C aryl group, 1-8C alkyl group or 1-8C alkoxy group, each of R2 , R3 and R4 represents a hydrogen atom, halogen atom, cyano group, 6-30C aryl group, diphenylamino group or 1-8C alkyl group, each of X and X' represents an oxygen atom, sulfur atom, selenium atom, propane-2-diyl, butane-2-diyl, 3-6C cycloalkane-1,1-diyl, -NH- or -NY1 -, each of Y, Y' and Y1 represents a 1-30C organic group and each of r and r' represents an integer 0 to 2. |
