Basic Knowledge About Lighting

Item

Symbol

Unit

Description

Beam( Luminous Flux )

Φ

(Lm)

The sum of the light source issued every second, simple as glow amount.

Light Intensity

I

(Cd)

The strength of the light, the amount of radiation in a particular direction angle.

Illuminance ( Luminance Meter)

E

(Lm/m²)

The amount of radiation in unit area, that is the value of beam divided by area (m²), to indicate the brightness of some place.

Color Temperature (Color Temperature Meter)

K

(K)

When the color issued by the light source is same as the color radiated under a certain temperature by “blackbody”, the temperature of the “blackbody” becomes the color temperature of this light source.  The higher temperature of “blackbody”, the more blue color component in the light spectrum, and the less red color component. E.g. The light color of filament lamp is warm white, the color temperature is 2700K, and however, the color temperature of daylight fluorescent lamp is 6000K.

Item

Description　

Photochromic

Photochromic actual is color temperature, which roughly divided into three types: warm color<3300K; intermedium color 3300~5300K; daylight color >5300K, due to the different composition of light spectrum from light, even if the same light color, the color rendering may be the different.

Color Rendering

In principle, artificial light should be the same as natural light, and could distinguish the color correctly with the naked eye.  Of course, this according to the site and aim of the lighting.  The degree of the present color of the object by the light source called color rendering, also called “color-rendering index” (Ra)

Luminaire Efficiency

Luminaire efficiency（Light output coefficient）is an important standard to measure the energy utilization of luminaires.  It is the ratio between the output luminous flux of the lamp and the inside light of lamp.

Light Source Efficiency

The amount issued by each watt of electricity, the higher value, the higher light source efficiency.  So address to the place use for a long time, like office corridor \ roads \ tunnel. etc. Efficiency is an important considerable factor.

Brightness ( Brightness Meter )

The unit projective plane of light source in a certain direction, and the quantity of the reflected light from the unit projective plane in the unit solid angle,which means the brightness of the light source in one direction. Symbol：L　L＝di/ds; unit is cd/m²

Glare

Glare means that there is a high brightness object or strong brightness contrast within the field of vision, and make it uncomfortable.  Glare can be divided into disability glare and discomfort glare.  It’s an important factor which can influence the illuminating quality.

Power Factor

As the ratio of actual power and apparent power ( the product of power and current) in circuit.

Average Life

Beam Angle

Included angle between maximum light intensity of the 1/10 lamps.