1. By Color
LEDs are available in red, orange, blue, green (subdivided into yellow-green, standard green and pure green) and so on. Besides, some light emitting diodes have chips with two or three colors. In addition, the package (plastic body) of LED may have light scattering agent or not, be color or colorless, so, LED can be classified into 4 different types—colored transparent, water white transparent, colored scattering and colorless scattering. Scattering LED is often used in indicator lamps.
2. By outer surface traits
It can be classified into round LED, square LED, rectangular LED, surface LED, side LED, surface mount subminiature LED and so on.
Round LEDs are divided into the following types according to its diameter: φ2mm, φ4.4mm, φ5mm, φ8mm, φ10mm and φ20mm and so on. φ3mm LED is often noted as T-1, φ5mm T-1(3/4) and 4.4mm T-1(1/4). The angle distribution condition of round LED’S luminous intensity can be evaluated by the value of its viewing angle. According to angle distribution of luminous intensity, it can be classified into three types:
1) High directivity. 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. It’s usually used as indicator lampindicator lampindicator lamp. The viewing angle is between 20° and 45°.
3. By structure
It is divided into full epoxy resin packaging, metal base, ceramic base epoxy resin packaging and glass packaging.
4. By luminous intensity and operating current
It can be classified into general LED (with luminous intensity less than 10mcd); high brightness LED (with luminous intensity between 10mcd and 100mcd); ultrahigh high brightness LED (with luminous intensity over 100mcd).
General LEDs run at an operating current from over 10mA to tens mA while low LED operating current runs below 2mA (with the same brightness as general LED).
Besides, there are also classifications according to the chip materials and functions.