| 摘要 |
864,011. Diazotype materials and processes. LANDAU, R. March 17, 1958 [March 16, 1957], No. 8513/58. Drawings to Specification. Class 98(2) Diazotype material contains one diazo compound which is converted by radiation in a given wavelength band into a coupling component, and another diazo compound of greater coupling energy than the first which will couple with the coupling component formed from the first diazo compound and which is decomposed by radiation of a wavelength band different from the first band. The wavelength bands may be ultra-violet and infra-red or visible light. The material is first exposed through the document to be copied using radiation of one of the wavelengths, and then the original is removed and the material given a uniform second exposure of the second wavelength. If the diazo which gives the coupler is sensitive to ultra-violet and the other diazo is sensitive to infra-red, then a first exposure to infra-red and a second exposure to ultra-violet gives a positive. Conversely, if the diazo which gives the coupler is sensitive to infra-red and the other diazo to ultra-violet, a positive is produced by a first exposure to ultraviolet and a second exposure to infra-red. Reversing the order of exposure in either case yields a negative. Diazo compounds which produce couplers and diazos of the normal type are listed which are sensitive to infra-red or ultra-violet light only. |
