The earliest luminous material used was zinc sulfide. Zinc sulfide itself does not emit light, but has a phosphorescent property, that is, it is excited after being irradiated by sunlight or light, and the light is continuously emitted for a certain period of time. However, the decay rate of zinc sulfide is very fast, and there is no light in the dark for a while. This zinc sulfide is harmless. In 1898, Mrs. Curie discovered the radioactive element radium. At that time, it was found that if radium and zinc sulfide were mixed, then zinc sulfide would glow by itself, no longer. It can also be stimulated by the need for sunlight or light. In this way, this "cross-age" luminous material began to spread rapidly. Since the 1930s, the night light used on clocks has been basically this material. If you use radium as a luminous material, it must be harmful to humans.
In 1949, this kind of luminous light began to use this material, but it is also a radioactive element. Although it is not as harmful to the human body as the luminous material, it will still be exposed to extremely small radiation hazards when wearing the watch. When the luminous watch is removed, there is no direct radiation. This is why the root of the "Night Watches to Remove When Sleeping at Night" has been circulating. This kind of night light has been used since the 1950s until the 1990s.
Some brands now use a helium tube. The xenon tube is coated with a thin layer of zinc sulfide on the inner wall of the glass tube, and then the tube is filled with helium. The helium in the tube stimulates the continuous glow of zinc sulfide, which lasts for 20 years. Moreover, the greater the helium pressure filled in the glass tube, the greater the brightness of the light. Of course, this technology is also radiation, but "the dose is a hooligan." In fact, the radiation hazard of using a ruthenium material as an excitation element is very small, equivalent to no. Its ray and sapphire crystal are difficult to penetrate, even if the snoring of the snoring tube, the harm of the sputum to the human body is not worth mentioning.
Although the night light has only a small amount of radiation, it is still not completely safe. With the development of technology, modern luminous watches began to use the new luminous material Super-LumiNova, which is a no-radiation, non-toxic night light, composed of barium aluminate salt and rare earth compounds. Japan's Nemoto&Co. Ltd. It is the patent holder of Super-LumiNova Luminous, invented in 1993, and it is the same as Swiss RC TRITEC Ltd. The joint venture LumiNova AG Switzerland was established to supply this high-quality luminous material to the world. Super-LumiNova is not only radiation-free, non-toxic, but also has excellent night light effect. In the early stage of luminescence, Super-LumiNova can exceed the snorkel tube and its strength is even 100 times higher than that of traditional zinc sulphide.