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| US4181439 | 14 Mar 1977 | 1 Ene 1980 | Cerberus AG | Smoke detector with a conical ring-shaped radiation region |
| US4216377 | 22 Jun 1978 | 5 Ago 1980 | Nittan Company, Limited | Light scattering smoke detector |
| US4225791 | 1 Mar 1979 | 30 Sep 1980 | Honeywell Inc. | Optical smoke detector circuit |
| US4269510 | 9 Oct 1979 | 26 May 1981 | Cerberus Ag | Smoke detector |
| US4291983 | 22 May 1979 | 29 Sep 1981 | American Home Products Corporation | Photometric apparatus and method |
| US4311388 | 25 Oct 1979 | 19 Ene 1982 | Societe Nationale d'Etude et de Construction de Moteurs d'Aviation | Visibility measuring device |
| US4430646 | 31 Dic 1980 | 7 Feb 1984 | American District Telegraph Company | Forward scatter smoke detector |
| US4488812 | 29 May 1981 | 18 Dic 1984 | American Home Products Corporation | Photometric apparatus |
| US4607915 | 13 Ago 1984 | 26 Ago 1986 | | Light absorbers |
| USRE32105 | 19 Nov 1984 | 1 Abr 1986 | American District Telegraph Company | Forward scatter smoke detector |
