Clear to colored security film
First Claim
Patent Images
1. A multilayer film comprising alternating layers of at least a first polymer and a second polymer;
- the film appearing substantially clear at approximately a zero degree observation angle, and colored at at least one observation angle greater than a predetermined shift angle wherein the film comprises a series of layer pairs having optical thicknesses of between approximately 360 nanometers and approximately 450 nanometers.
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Accused Products
Abstract
A multilayer film including multiple polymeric layers designed and made to enable the film to reflect light in the near infrared (IR) portion of the visible spectrum. Depending on the amount and range of red light that is reflected, the film of the present invention appears under certain conditions to exhibit a visible color, commonly cyan. The film appears to be substantially clear when viewed against a diffuse white background from approximately a zero degree observation angle, and appears to be cyan when viewed against that background from an observation angle that is greater than a predetermined shift angle.
283 Citations
39 Claims
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1. A multilayer film comprising alternating layers of at least a first polymer and a second polymer;
- the film appearing substantially clear at approximately a zero degree observation angle, and colored at at least one observation angle greater than a predetermined shift angle wherein the film comprises a series of layer pairs having optical thicknesses of between approximately 360 nanometers and approximately 450 nanometers.
- View Dependent Claims (3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
- 2. A multilayer film comprising alternating layers of at least a first polymer and a second polymer, the film transmitting substantially all incident visible light and reflecting light having a wavelength of from approximately 720 to 900 nanometers at approximately a zero degree observation angle, and transmitting substantially all visible light except a selected portion of red light at at least one observation angle greater than a predetermined shift angle.
Specification