According to the characteristics of the light emitting surface of the luminous tube
According to the characteristics of the light-emitting surface of the luminous tube, it can be divided into round lamps, square lamps, rectangular, surface luminous tubes, lateral tubes, and microtubes for surface mounting. Round lights are divided into φ2mm, φ4.4mm, φ5mm, φ8mm, φ10mm and φ20mm according to their diameters. In foreign countries, light-emitting diodes with φ3mm are usually referred to as T-1; those with φ5mm as T-1(3/4); and those with φ4.4mm as T-1(1/4).
The angular distribution of circular luminous intensity can be estimated from the half-value angle.
There are three categories from the angular distribution of luminous intensity:
(1) High directivity. Generally, it is a pointed epoxy package or a package with a metal reflective cavity, and no scattering agent is added. The half-value angle is 5°~20° or less, with high directivity, and can be used as a local lighting source, or combined with a light detector to form an automatic detection system.
(2) Standard type. Usually used as indicator light, its half-value angle is 20°~45°.
(3) Scattering type. This is an indicator light with a larger viewing angle, the half-value angle is 45°~90° or greater, and the amount of scattering agent is larger.
