Abstract:
There is described an optical-effect-producing medium comprising a carrier medium (1 ) containing or comprising pigment particles (10) having at least one optically responsive pigment or dye (100) that responds to incident electromagnetic radiation of at least a selected excitation wavelength or wavelength band (??X) by producing an optical response in the visible or near- visible spectrum. A refractive index (n1 ) of the carrier medium (1 ) and a refractive index (n2; n3) of the pigment particles (10) are selected to maximise the amount of incident electromagnetic radiation reaching the said at least one optically responsive pigment or dye (100). Also described is the use of such optical-effect-producing medium to produce an optically responsive feature, especially for security, authentication and/or identification purposes, as well as objects comprising such an optically responsive feature.
Abstract:
A spheroidal ball comprising a plurality of segments arrayed substantially parallel to one another, each segment being adjacent to at least one other segment and to no more than two other segments, adjacent segments being adjoined to one another at substantially planar interfaces, the plurality of segments including a first segment having a first thickness and a first optical modulation characteristic, a second segment having a second thickness and a second optical modulation characteristic, and a third segment having a thickness different from at least one of the first and second thicknesses and an optical modulation characteristic different from at least one of the first and second optical modulation characteristics, the ball having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field.
Abstract:
A spheroidal ball comprising a plurality of segments arrayed substantially parallel to one another, each segment being adjacent to at least one other segment and to no more than two other segments, adjacent segments being adjoined to one another at substantially planar interfaces, the plurality of segments including a first segment having a first thickness and a first optical modulation characteristic, a second segment having a second thickness and a second optical modulation characteristic, and a third segment having a thickness different from at least one of the first and second thicknesses and an optical modulation characteristic different from at least one of the first and second optical modulation characteristics, the ball having an anisotropy for providing an electrical dipole moment, the electrical dipole moment rendering the ball electrically responsive such that when the ball is rotatably disposed in a nonoscillating electric field while the electrical dipole moment of the ball is provided, the ball tends to rotate to an orientation in which the electrical dipole moment aligns with the field.
Abstract:
There is described an optical-effect-producing medium comprising a carrier medium (1 ) containing or comprising pigment particles (10) having at least one optically responsive pigment or dye (100) that responds to incident electromagnetic radiation of at least a selected excitation wavelength or wavelength band (λ ΕX ) by producing an optical response in the visible or near- visible spectrum. A refractive index (n 1 ) of the carrier medium (1 ) and a refractive index (n 2 ; n 3 ) of the pigment particles (10) are selected to maximise the amount of incident electromagnetic radiation reaching the said at least one optically responsive pigment or dye (100). Also described is the use of such optical-effect-producing medium to produce an optically responsive feature, especially for security, authentication and/or identification purposes, as well as objects comprising such an optically responsive feature.
Abstract:
This invention generally relates to the use of dipole charged balls having differently coloured hemispheres (bichromal balls) in twisting ball displays comprising a pair of planar addressing electrodes and the space between these electrodes that is filled with a thixotropic liquid into which has been dispersed a plurality of electrically charged and optically anisotropic rotatable elements.
Abstract:
A gyricon or twisting-particle display based on nonspheroidal (e.g., substantially cylindrical) optically anisotropic particles disposed in a substrate. The particles can be bichromal cylinders, preferably aligned parallel to one another and packed close together in a monolayer. A rotatable disposition of each particle is achievable while the particle is thus disposed in the substrate; for example, the particles can already be rotatable in the substrate, or can be rendered rotatable in the substrate by a nondestructive operation performed on the substrate. In particular, the substrate can be made up of an elastomer that is expanded by application of a fluid thereto so as to render the particles rotatable therein. A particle, when in its rotatable disposition, is not attached to the substrate. The close-packed monolayer configuration of particles provides excellent brightness characteristics and relative ease of manufacture as compared with certain other high-brightness gyricon displays. The substrate containing the cylinders can be fabricated with the swelled-elastomer techniques known from spherical-particle gyricon displays, with a simple agitation process step being used to align the cylinders within the sheeting material. Techniques for fabricating the cylinders are also disclosed.