What is a luminous watch? What is the difference between a luminous watch and an electroluminescent watch

　　What is a "luminous watch"? How does it differ from an electroluminescent watch

　　The watches we commonly refer to as " luminous watches " generally feature hands or indices coated with fluorescent powder, known as luminous coating, which allows for clear time reading in the dark. Luminous powder is based on zinc sulphide; it does not emit light itself but possesses phosphorescent properties, meaning it is excited after exposure to sunlight or artificial light and will continue to glow for a certain period. Another type of light-emitting watch is the electroluminescent watch, which appeared in the mid-nineties and allows the entire dial to illuminate.

　　The differences between the two are as follows:

　　1, luminous watches emit light by absorbing natural light energy, whereas electroluminescent watches rely on battery power to emit light.

　　2, the " luminescence " of a luminous watch is only visible in low-light conditions, whereas an electroluminescent watch can emit light at any time by pressing the corresponding button.

　　3, the duration of luminescence for a luminous watch is limited by the duration and intensity of light absorption, while electroluminescence is limited by battery power.

　　Are luminous watches radioactive?

　　To ensure zinc sulphide is continuously excited, luminous watches must be mixed with a certain amount of radioactive elements. Radium was commonly used in the past, while promethium (a radioactive element whose beta rays can cause phosphors to glow) is more common today. The brightness of the luminescence varies according to the dosage of the radioactive element. Radioactive elements not only excite the luminous material but also gradually destroy its structure, causing its performance to weaken and eventually disappear, which is why luminous watches become less bright after a certain period of use. Although this layer of radioactive material is applied very thinly, long-term wear can still cause harm to the human body. Scientists later sought new luminous coatings to replace radioactive radium salts, and currently, tritium is used instead (tritium is also radioactive). In recent years, manyReplica watchesalso adopt more advanced materials, with light-storage materials moving towards non-toxic and non-radioactive development. Light-storage materials obtained by high-temperature sintering of aluminium and barium-strontium series doped with rare earth elements offer brightness that surpasses traditional materials.

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