Differences and connections between illuminance（Lx） and brightness(Cd/m2) concepts

In daily life, families, schools, factories, and public places are widely used in various lamps and lanterns. The lamp is one of the most meaningful inventions of the twenty-first century. With lights, people say goodbye to darkness. The street lights on the road give people a sense of security, and the lighthouse in the sea guides the course of the ship. It can be said that people can't live without lights nowadays, and when the power goes out at night, people will be very inapplicable.

Light is so important, and when people talk about light, it involves illuminance and brightness. Most people think they are the same in their consciousness, but in fact they are not.

How are they different from a scientific point of view?

Illuminance, to put it simply, is the amount of light (luminous flux) of the bulb that is incident on a surface with the desired amount of intensity (light intensity) from a certain place, so that the illuminance can be calculated.

Brightness refers to the degree of light that something emits or reflects to the naked eye.
     In a certain sense, the color of the surface of an object, such as red, purple, steel, or mud lime, does not make much difference in illuminance, and can reflect light, from a physical point of view, it is specular or diffuse reflection, in a A room full of sunlight can see different ways of reflecting light.
     The effect of illuminance and brightness on people
     It can be said that all indoor space lighting should examine the relevant horizontal illuminance, such as color temperature. Like most of the time at work, it is not enough to only pay attention to the light color in the workplace, and the illuminance must be considered.
     If the illumination value is large, and the color temperature is relatively small, there will be a sultry experience. If the illumination is too low, and the color temperature is too large, it can cause depression and fatigue, which is not good for people to work and study. So they are also a very important part.
     In 2020, the workplace lighting specification stipulated by the mainland is between 300lx-500lx, which is an ideal and reasonable value.
     For restaurants like this, the light should be compounded at about 200lx.