Light terminology

Luminous luminous flux (luminous flux) Unit: lumens (lm), the sum of light emitted by a light source per unit of time is called the luminous flux of the light source.

Luminous intensity unit: Candela (CD). The luminous flux emitted by a light source within a unit solid angle in a given direction is called the luminous intensity of the light source in this direction, and is simply called the luminous intensity.

Illuminance Unit: Lux (lx), the illuminance is the luminous flux that the light source irradiates on the unit area of ​​the illuminated object.

Luminance (luminance) Unit: Candela per square meter (CD/m2), Nit (nt) is the name of the old brightness unit and has been repealed. The brightness of a light source in a certain direction is the ratio of the light intensity of the light source in the same direction and the surface area of ​​the light emitting surface in that direction.

Luminous efficacy of light source Unit: lumens/watt (lm/W). The ratio of the total luminous flux emitted by a light source to the electric power (watts) consumed by the light source is called the luminous efficacy of the light source.

Average life unit: Hours (h), the number of hours that a point of lamp ignition occurs when 50% of the lamps fail to light.

The color temperature CT-colour temperatur e, when the color of the light emitted by the light source is the same as the color emitted by the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source, and is represented by the absolute temperature K (kelvim). The theory of black body radiation is based on heat radiation. Therefore, the spectral power distribution of a heat radiation source such as incandescent light is close to the spectral power distribution of the black body in the visible region. Both are continuous spectra, and the concept of color temperature can fully describe this. The color characteristics of the class light source. Correlated color temperature CCT-correlated colour temperature, when the color of the light emitted by the light source is close to the color of the black body radiating at a certain temperature, the temperature of the black body is called the correlated color temperature of the light source, and the unit is K. Because of the gas discharge light source For the non-continuous spectrum, the continuous spectrum of blackbody radiation cannot be completely consistent, so the correlated color temperature is used to approximate the color characteristics. The color temperature (or correlated color temperature) of the light source below 3300K is reddish and gives a warm feeling. When the color temperature exceeds 5300K, the color is blue, giving a feeling of cooling. In regions with higher temperatures, people usually use light sources with a color temperature higher than 4000K, while those with lower temperatures use light sources below 4000K.

The color rendering index (Ra) colour rendering index, the continuous spectrum of sunlight and incandescent lamp radiation, in the range of visible light wavelength (380nm-760nm), including red, orange, yellow, green, blue, blue, purple and other Color light. The object displays its true color under sunlight and incandescent light, but when the object is exposed to a non-continuous spectrum gas discharge lamp, the color will have different degrees of distortion. We refer to the degree of representation of the light source to the true color of the object as the color rendering of the light source. In order to quantitatively evaluate the color rendering of a light source, the concept of a color rendering index was introduced. According to the standard light source, the color rendering index is set to 100, and the color rendering indices of the remaining light sources are all lower than 100. The color rendering index is represented by Ra. The larger the Ra value, the better the color rendering of the light source.