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US 2003/0151786 A1Published application
Optical security device
OwnerJohn Drinkwaterinventor
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OwnerJohn Drinkwaterinventor
Estimating the term…
A holographic effect generating structure (HEGS), either stand alone or integrated with a security diffractive image, generates a holographic optically varying image by a process of diffraction of light, this image under white light illumination generates a smoothly and continuously variable structureless optically variable apparent motion effect which moves along a pre-determined track within pre-determined limits, the device characterised that it generates 3 planes of images under white light illumination an image plane image located at or near the image plane corresponding to the real plane of the device which defines the predetermined movement track of the apparent motion effect and its bounds, a second virtual image plane situated away from the image plane of the device forming a virtual viewing zone corresponding at which an observer would be positioned to observe the visual effect and a third image plane, which defines a region where all the light rays from the image plane artwork to the viewing zone pass through or appear to originate from which defines the defines the viewing track of the apparent motion effect.
An optical security device comprising a discrete region containing a diffractive structure arranged to generate a holographic optically variable image comprising a continuously variable arrangement of diffractive spatial frequencies wherein upon illumination by white light the structure generates a visible_optically variable image viewable by an observer in which the diffractive replay of the image is characterised by a continuous smooth apparent motion effect observed when the device is tilted, and wherein the said replay occurs in relation to a defined graphical image located at least in proximity to an image plane of the device.
An optical security device as claimed in any one of the preceding claims comprising a plurality of diffractive optical structures arranged so as to replay under white light illumination at least two different forms of apparent motion effects viewable by an observer when the device is tilted.
An optical structure as claimed in any one of the preceding claims arranged integrally with a security hologram, security diffractive structure, rainbow hologram, or the like.
An optical security device as claimed in any one of the preceding claims wherein the diffractive image is arranged to replay within an area defined by an image plane artwork associated with the structure.
An optical security device comprising an optical structure arranged to generate a holographic optically variable image which, when illuminated by white light, generates a continuously variable motion effect moving along a predetermined track, and also arranged to generate three image planes comprising a first image plane located at least in proximity to the image plane corresponding to the real plane of the device which serves to define a predetermined movement track of the apparent motion effect, a second image plane situated away from the real plane of the device and forming a virtual viewing zone corresponding to a rainbow slit and corresponding to a viewing track of an observer when viewing the motion effect, and a third image plane in the form of a parallax barrier.
An optical security device as claimed in any one of the preceding claims wherein the diffractive optical structure is in the form of a surface relief structure.
A method of recording an optical structure on an optical security device and offering holographic artwork and an H1 rainbow slit and including the step of introducing a mask specifically for defining a parallax barrier arranged to be located between holographic artwork and an H1 rainbow slit.
An optical security device comprising an optical structure arranged to generate a holographic optically variable image and as substantially hereinbefore described with reference to, and as illustrated in, the accompanying drawings.
A method of recording an optical structure on an optical security device substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.
Dependencies are inferred from the claim text.