According to the characteristics of the light emitting surface, it can be divided into round lamp, square lamp, rectangle, face light emitting tube, side tube, micro tube for surface mounting, etc. The circular lamp is divided into φ 2mm, φ 4.4mm, φ 5mm, φ 8mm, φ 10mm and φ 20mm according to its diameter. In foreign countries, the light-emitting diode of φ 3mm is usually recorded as T-1; the LED of φ 5mm is recorded as T-1 (3 / 4); and the LED of φ 4.4mm is recorded as T-1 (1 / 4).
The angular distribution of circular luminous intensity can be estimated from the angle of half value.
From the angle distribution of luminous intensity, there are three types:
(1) High directivity. In general, it is a sharp epoxy package, or a package with a metal reflecting cavity, and no scattering agent is added. The half value angle is 5 ° ~ 20 ° or less, which has high directivity. It can be used as a local lighting source, or combined with a light detector to form an automatic detection system.
(2) Standard. It is usually used as an indicator lamp with a half value angle of 20 ° ~ 45 °.
(3) Scattering type. This is an indicator light with a large viewing angle, with a half value angle of 45 ° ~ 90 ° or more, and a large amount of dispersant.