Classification of LED products
LED which is becoming widespread owns various kinds of product. LED products can be classified into different types according to light emitting colors, outer surface trait and structure of the diodes, luminous intensity, operating current, chip material, function and etc. This passage is going to introduce four types of LED products classification.
1. According to light emitting colors of the diode:
LEDs are available in red, orange, green (subdivide into yellow-green, standard green and pure green) and blue and so on.
Some light emitting diodes have chips that bear two or three colors. Besides, the package (the plastic body) of LED may have light scattering agent or not, be colored or colorless, thus, LED can also be classified into the following four types: colored transparent, colorless transparent, colored scattering and colorless scattering.
2. According to the outer surface (plastic body) traits of the diode, LED can be classified into round LED, square LED, rectangular LED, surface LED, side LED, surface mount subminiature LED and so on.
Round LED can be divided into following types according to its diameter: φ2mm、φ4.4mm、φ5mm、φ8mm、φ10mm and φ20mm and so on. Round LED with diameter of φ3mm is generally noted as T-1 in abroad, φ5mm noted as T-1(3/4) and φ4.4mm noted as T-1(1/4).
The angle distribution condition of round LED’s luminous intensity can be evaluated by the value of its viewing angle. The following three types are classified according to the angle distribution of the luminous intensity:
(1) High directivity LED: This kind of LED generally adopts sharp head epoxy packaging or metal reflection cavity packaging, usually without light scattering agent. The viewing angle of this kind of LED varies between 5° and 20° or even smaller. With high directivity, it can be used as local illumination source or to build up an automated detecting system together with a light detecting machine.
(2) Standard type: It is generally used as indicator lamp. The viewing angle varies between 20° and 45°.
(3) Scattering type: Its is usually applied as indicator lamp that has comparatively bigger viewing angle which varies between 45° and 90° or even larger. It has more light scattering agent than the other types.
3. According to the structure, LED can be classified into full epoxy resin packaging, metal base, ceramic base epoxy resin packaging and glass packaging.
4. According to the luminous intensity and operating current.
According to luminous intensity, there are standard brightness LED (with luminous intensity less than 10mcd), high brightness LED (with luminous intensity between 10mcd and 100mcd) and ultrahigh brightness LED (with luminous intensity larger than 100mcd).
LED can also be divided into two types according to its operating current: standard type which runs at an operating current from more than ten mA to tens mA; low current LED which runs at an operating current below 2mA (however, with the same brightness as standard LED).
TAG:  LED products