Optical polarizing films with designed color shifts
Assignee3M Innovative Properties Company
InventorsTimothy J. Hebrink, Laurence R. Gilbert, James M. Jonza, Andrew T. Ruff
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Abstract
Multilayer films are provided that exhibit a colored appearance when viewed at an oblique angle as a result of one or more reflection bands in the visible region of the spectrum. The films however provide no substantial reflection bands in either the visible or near infrared regions for light normally incident on the film. The films can be made to shift from clear at normal incidence to an arbitrary designed color at an oblique angle without necessarily becoming cyan.
Claims24
An optical film, comprising a first alternating layer of at least a first polymer and a second alternating layer of at least a second polymer, wherein the first polymer is substantially isotropic and the second polymer is birefringent, the alternating layers defining a coordinate system with mutually orthogonal x- and y-axes extending parallel to the layers and with a z-axis orthogonal to the x- and y-axes, wherein the alternating layers have a refractive index difference along the z-axis of 0.1 or greater, wherein the optical film has a reflection band covering a portion of the visible spectrum at an oblique angle such that the optical film appears colored at such oblique angle, and wherein the optical film has substantially no reflection bands for normally incident light.
An optical film, comprising a first alternating layer of at least a first polymer and a second alternating layer of at least a second polymer, wherein the first polymer is substantially isotropic and the second polymer is birefringent, the alternating layers defining a coordinate system with mutually orthogonal x- and y-axes extending parallel to the layers and with a z-axis orthogonal to the x- and y-axes, wherein the alternating layers have a refractive index difference along the z-axis of 0.1 or greater, and wherein the sum of the optical thickness of the first alternating layer and the optical thickness of the second alternating layer is 200 nm to 350 nm.
An optical film comprising a first portion and a second portion, wherein the first portion has a different overall thickness than the second portion, wherein the first portion and the second portion define indicia, and wherein the optical film has a reflection band covering a portion of the visible spectrum at an oblique angle such that the optical film appears colored at such oblique angle, and wherein the optical film has substantially no reflection bands for normally incident light.
Dependencies are inferred from the claim text.