Ccl Secure Pty Ltd

Cll Secure Pty Ltd

Phei Lok

Gary Fairless Power

Robert Arthur Lee

Odisea Batistatos

Benjamin Stevens

High refractive index coatings having metal oxide particles are disclosed. Dispersions of metal oxide particles in solvent are also disclosed. These find use in the protection of surface relief structures. In some disclosed embodiments, the coatings or dispersions contain UV-curable resins. The coatings and dispersions find application in the field of security devices and documents and tokens incorporating security devices.

High refractive index coatings and their use in the protection of surface relief structures

An optically variable device and method of manufacturing the device is disclosed, the device including a plurality of zero-order diffraction grating elements some of which are modulated such that a coloured at least partially polarized image is visible to a person viewing the device, observing a first optically variable effect when the device is rotated about an axis substantially perpendicular to the plane, and a second optically variable effect when the device is viewed under polarized light and rotated about an axis substantially perpendicular to or parallel with the plane. The device is particularly suitable for security documents such as bank notes. Preferably, the first optically variable effect is produced by a change in brightness and/or color of the grating elements and the second optically variable effect may likewise be produced by a change in brightness and/or color of the grating elements. The device advantageously provides two different types of optically variable effect may be provided in a single device. This is possible due to the use of zero-order grating elements as the 'pixels' of the colored image. Each pixel, under illumination by unpolarized light, produces reflected light of a defined color which is also at least partially polarized.

Optically variable device

An optical security device is disclosed which includes a diffraction layer having a plurality of diffraction elements and a high refractive index layer, wherein the high refractive index layer is applied on the diffraction layer such that selected regions of the diffraction layer have the corresponding diffraction elements partially uncovered by the high refractive index layer and other regions are substantially covered by the high refractive index layer. Accordingly, the optical security device has a first security feature associated with the diffraction layer and a second security feature associated with the high refractive index layer. An image is viewable from the regions of the high refractive index layer, either, covertly by placed an index matched item over the device or, overtly, through selection of the thickness of the high refractive index layer.

Optical security device having a high refractive index layer between adjacent diffraction elements which have upper portions uncovered by the high refractive index layer

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Craigieburn, Australia

Phei Lok