According to its name, the electric light source mainly has two performance indicators of light and electricity. Of course, the performance indicators of these two aspects are closely related. However, as a light source, it is mainly the performance index of light, and the indicators of electricity often focus on its influence on light performance.

(1) Luminous flux

The luminous flux of the light source represents the luminous ability of the light source and is an important indicator of the light source. The rated luminous flux of the light source refers to the luminous flux output of the light source under the conditions of rated voltage and rated power, and can emit light without restraint.

The luminous flux of the light source will change with the ignition time of the light source, that is, the longer the ignition time, the smaller the luminous flux becomes due to attenuation. The luminous flux of most light sources attenuates more at the initial stage of ignition, and the attenuation gradually decreases with the increase of ignition time. There are two cases for the rated luminous flux of the light source: one refers to the initial luminous flux of the electric light source, that is, the luminous flux output when the new light source starts to ignite. The other case refers to the luminous flux output of the light source after 100 hours of use, which is generally used for light sources with large luminous flux attenuation, such as fluorescent lamps.

(2) Luminous efficiency

The ratio of the luminous flux output of the light source to the electric power it uses is called the luminous efficiency of the light source, or luminous efficiency for short, and the unit is lm/w. Light sources with high luminous efficiency should be preferred in lighting design.

(3) Color rendering

Color rendering is an important performance indicator of light sources. Under normal circumstances, the color rendering index of the light source is generally used to measure its color rendering, which can be roughly divided into 4 groups. When there are special requirements for certain colors, a special color rendering index is used.

Application example of color rendering index of light source

(4) Color table

The color table of the light source refers to its apparent color, which is two different concepts from the color rendering of the light source. For example, the light of fluorescent high-pressure mercury lamp is white and bright from a distance, and the color table is good, but the face of the person under the light is cyan, indicating that its color rendering is not very good. Color table is also an important performance index of electric light source.

Although the color table of the light source can be expressed by adjectives such as red, orange, yellow, green, cyan, blue, purple, etc., in order to quantitatively express it, it is often measured by the correlated color temperature. The color table of light sources can be divided into three categories according to their correlated color temperature.