Luminous watches need to absorb 3-4 hours of light. Night watch is a kind of modern popular watch, which can automatically emit light at night. Usually, ordinary night-light meters absorb sunlight for about 3-5 hours to reach saturation. Usually, the luminous time of luminous watches is not proportional to the luminous time, so special attention should be paid when using them.
Luminous watches need energy to shine at night, mainly to absorb ultraviolet rays from the sun during the day. There are two kinds of common noctilucent meters, one is the light storage type noctilucent meter, the longer the light absorption time, the longer the light will be on, and the other is the self-luminous type, which mainly relies on noctilucent powder to emit light.
However, self-luminous materials are generally radioactive and harmful to human health. If the watch is made of luminous material, for example, the internal hands are luminous hands, this material and light have no effect. Even if it doesn't accept light energy, it can emit light, but the light is weak.