What are the hidden dangers of unqualified classroom blackboard lights
Nowadays, students studying and living on campus rely on the lighting of the classrooms. According to surveys, many schools have greatly improved the lighting comfort of students in the process of studying in the school through the renovation of classroom lighting. So, what is the current situation of classroom lighting? What are the hidden dangers of classroom blackboard lights? Let's take a look now!
From a physiological point of view, the human eye is like a sophisticated optical instrument, which can perceive a wide range of brightness, and can distinguish objects ranging from a few thousandths of nits to millions of nits. When my country began to implement the "Hygienic Standards for Daylighting and Lighting in Primary and Secondary School Classrooms", it was required that the illuminance of the classroom desktop should reach 300Lx, and the illuminance of the blackboard surface should reach 500Lx.
However, some schools have very low blackboard pass rates. The main reason is that the angle of the lamps installed on the blackboard is not good, and the lighting function of the lamps cannot be fully utilized, resulting in uneven light projected on the blackboard; in some classrooms, only one lamp is installed in front of the blackboard, and there is no lighting even in front of the blackboard. In some classrooms, the average illuminance of the blackboard is only 66lx.
During the day, when the ambient brightness reaches 10000nit, the human eye can distinguish the brightness range of about 200-20000nits, and the brightness below 200nit will be regarded as black; when the environment is 30nit at night, the distinguishable brightness range is 1-200nit . At this time, when the brightness is 100 nit, it will produce a quite bright feeling, and only the brightness below 1 nit will produce a black feeling.
Human visual perception depends on the adjustment of pupils and photoreceptor cells. The size of the pupil is adjusted according to the intensity of external light. Photoreceptor cells are divided into cone cells and rod-shaped cells. The sensitivity of the latter is 10,000 times that of the former. Under strong and weak light, the pupils and photoreceptor cells adjust to each other, so that the light flux on the retina is kept moderate. Therefore, if the blackboard is too weak or too weak, it will have a bad influence on the students.
Daily lighting must conform to people's visual laws and eye health. Without reducing the quality of lighting, reduce energy consumption and realize "green lighting", that is, scientific and healthy lighting.
