| 摘要 |
<p>A substrate, such as a banknote (10) or other document of value, is provided with a security feature in the form of an optically variable device (12), by a process which comprises applying a coating of an ink to a discrete area of the substrate (10) by a printing process, then impressing the ink coating using an impression die, to form a pattern of reflective grooves in the surface of the inked area, these reflective grooves forming an optically variable image under incident light.</p> |
