Basic knowledge needed for lighting system design

1.Light source

Light sources are divided into natural light sources and artificial light sources.

Natural light sources are divided into self-illuminating and non-self-illuminating. The most common self-luminous light is the light emitted by "combustion", such as lightning, sunlight (essentially nuclear fusion); the other category is bioenergy light sources, fireflies, multitubular jellyfish, and sea bamboo shoots. Non-self-luminous light sources include sky light and moon light.

Artificial light source: Artificial light source is a light source manufactured by humans. From combustion to electricity, common are: torches, oil lamps, candles, electric lamps (incandescent lamps, fluorescent lamps, high-voltage xenon lamps) and so on.

2.Color temperature

If the ratio of the absolute blackbody at a certain temperature to the spectral emission of an actual object at two wavelengths is equal, the temperature of the blackbody is called the color temperature of the object, also known as the colorimetric temperature or the spectrophotometric temperature.

Because the spectral emissivity of an actual object increases or decreases with wavelength, or increases or is approximately independent of wavelength, the color temperature of an object may be greater than, less than, or approximately equal to its true temperature. Use a colorimeter to measure the color temperature.

3.Average illumination

The luminous flux received per unit of light receiving area S is called illuminance E, and the unit is Lx.

The average illuminance is used to measure the brightness of a scene.

Average illuminance (Lx) = Lumen (lm) × utilization factor × maintenance factor ÷ area

lumen:

The luminous flux unit (lm) of the light source. The amount of light emitted by the light source in a unit time is called the luminous flux F. The higher the number of lumens, the brighter the brightness.

Utilization factor:

The utilization factor is the ratio of the luminous flux received directly or through mutual reflection on the working reference plane to the sum of the rated luminous flux emitted by all the lamps of the lighting device. In order to avoid large deviations, there must be an accurate utilization factor in the lighting design. (Definition from Baidu Encyclopedia)

The main factors affecting the utilization factor are the light distribution curve of the lamp, the light output ratio of the lamp, the indoor reflection coefficient, and the arrangement of the lamp.

Maintenance factor:

After a period of work, the ratio of the average illuminance (that is, the maintenance illuminance) produced by the lighting system on the work surface to the average illuminance (that is, the initial illuminance) when the system is newly installed. (Definition from Baidu Encyclopedia)

This coefficient relates to whether the average illuminance of the luminaire after one year of use can maintain the standard.

The main factors that affect the maintenance factor are the exhaust value of fluorescent tubes, and the adhesion dust of fluorescent tubes and lamps.

4, color rendering

The color rendering ability of a light source to an object is called color rendering, and it is a comparison of the appearance color of an object under the same color temperature reference or a reference light source (incandescent lamp or painting light). There are two cases:

Faithful color rendering: A light source that can accurately represent the original color of a substance has a high color rendering index (Ra), a value close to 100, and the best color rendering.

Effect color development: Use the color addition method to enhance the color development effect, so as to emphasize specific colors more clearly. For example, a low color temperature light source is used to make red more vivid; a medium color temperature light source is used to make blue cool; a high color temperature light source is used to make objects feel cold.

The relationship between the color rendering index and color rendering: When there is little or no main wave reflected by the object under the reference light source in the light source spectrum, the color will have a significant color difference. The larger the color difference, the light color rendering of the color Worse. The color rendering index of incandescent lamp is defined as 100, which is an ideal reference light source.