| 摘要 |
An optical security device is for securing documents of value, such as banknotes, against counterfeiting. It has a transparent substrate 2 defining opposed, parallel surfaces 4,6 and having a first array 8 of opaque, spaced microlines on or in one surface, and a second array 10 of spaced microlines on or in the opposite surface. The two arrays 8,10 are located laterally relative to one another such that when the device is viewed at a first viewing angle (Figure 1b) with the first array nearer the viewer, the microlines of the second array fill the spaces between the microlines of the first array, while when the device is viewed at a second viewing angle (Figure 1a), different from the first viewing angle, the microlines of the second array do not fill the spaces between the microlines of the first array. |
