| 摘要 |
A document such as an indentification card (10) is constructed as a laminate within which is a code (16) is concealed from human view. The document is read by an electro-optic reader means, if the reader uses a beam of light in the wavelength absorbed by the material with which the coded indicia is produced, but reflected by the background against which the coded indicia is "seen" by the beam. The card is a laminate of an upper lamina (11) and a lower lamina (12), each made of a synthetic resin which is printed with a person's identification (14) with an ink which is visible to the human eye but substantially transparent to wavelengths outside the visible range. Typically, both the upper and the lower laminae, are opaque to visible light, but the face through which the coded indicia is to be read by the reader, is transparent to the reader's beam. |
