| 摘要 |
<p>The system provides a multi-colour anti-copying system in which different parts of an image or text on the original document are printed in different colours on a background of a third colour, the colours being so selected that one part of the image or text drops out in the resultant copy on a first group of copying machines while another part of the image or text drops out in the resultant copy on a second group of copying machines. The system utilises the various colour responses of the different photoconductor materials mentioned above for inhibiting or preventing the reproduction of intelligible copy. For example, printing a blue, light green or yellow-green image on a yellow background will inhibit satisfactory reproduction of copies on machines using those photoreceptors which respond well to yellow, but which respond weakly to blue or green. In attempting to copy such a coloured original, the background colour on the original will 'print up' in the copy and thus will be strong or dense while the image colour will 'print down' and thus will be faded. The resultant copy will therefore lack contrast, making it unreadable or unintelligible.</p> |
