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What’s LED?

   

A Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n region into the p region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths.

 

Definition of Light sources

   

Name

SI Units

Description

Luminous
Intensity

Candela
cd

The luminous flux density per solid angle as measured in a given direction relative to the emitting source.

Luminous
Flux

Lumen(lm)

The rate of flow of light per unit of time, especially the flux of visible light expressed in lumens, frequently defined as one lumen per square meter (lm/m2).

Illuminance

Lux(lx)
lm/m2

The density of luminous power, also called “illumination.” One lumen of luminous flux, uniformly incident on 1 square foot of area, produces an illuminance of 1 footcandle; in SI units, one lumen of luminous flux, uniformly incident on 1 square meter of area, produces an illuminance of 1 lux.

Luminance

Nit
(cd/m²)

luminous flux incident on a unit area, The intensity of light per unit area of its source. 1 nit = 1 cd/m2

Luminance Efficiency

Watt(w)
lm/W

The light output of a light source divided by the total electrical power input to that source, expressed in lumens per watt. A light source with a higher lumen per watt value is more efficient.

 

Color Temperature

   

The measurement of color expressed in Kelvin (K). The reason this measurement is called a "temperature" is because it was derived from a theoretical object called a "black body radiator." When the radiator is heated, it changes from black to red to yellow to white to blue. The lower the Kelvin rating, the "warmer" or more yellow the light. The higher the rating, the "cooler" or more blue the light. See white balance.

   

Lighting

Approximate

Temperature

In Kelvin

   

Candle 
Indoor tungsten
Indoor fluorescent
Outdoor sunlight
Outdoor shade
North sky

1,800 K
3,000 K
4,000 K
5,500 K
7,500 K
28,000 K

Higher color temperatures (5,000 K or more) are cool (blueish white) colors, and lower color temperatures (2,700–3,000 K) warm (yellowish white through red) colors.

   

     
 

JIS IPX Waterproof Grade

 
 

JIS IPX 8

Submersible

The equipment is usable for continuous submersion in water under specified pressure

JIS IPX 7

Immersion resistant

Water shall not enter the enclosure when it is immersed in water under defined conditions

JIS IPX 6

Water tight

Direct jetting water from any direction shall not enter the enclosure

JIS IPX 5

Jet resistant

Direct jetting water from any direction shall have no harmful effect

JIS IPX 4

Splash resistant

Splashing water from any direction shall have no harmful effect

JIS IPX 3

Rain resistant

Falling rain at an angle up to 60 degrees from vertical shall have no harmful effect

JIS IPX 2

Drip resistant 2

Dripping water at an angle up to 15 degrees from vertical shall have no harmful effect

JIS IPX 1

Drip resistant 1

Vertically dripping water shall have no harmful effect

JIS IPX 0

-

 No Special Protection