SMD led according to the distribution map points (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 smaller, the rectifier bridge has a high directivity, which can be used as part of the illumination light source, or used with a light detector to form an automatic detection system. (2) Standard type. It is generally used as an indicator light, and its half-value angle is 20. ~45. (3) Scattering type. This is an indicator with a larger viewing angle, with a half-value angle of 45. , 90. or larger, the amount of scattering agent is larger. SMD LEDs are divided into LEDs with general brightness according to luminous intensity and operating current (luminous intensity of 100mcd); those with luminous intensity between 10 and 100mcd are called high-brightness light-emitting diodes. The operating current of the general SMD LED is in the range of tens of mA to several tens of mA, while the operating current of the low current D is below 2 mA (the brightness is the same as that of the general light-emitting tube, and the characteristics of the SMD LED are small size, low power consumption, long service life, High brightness, environmental protection, sturdy, durable and reliable, suitable for mass production, fast response, shockproof, energy saving, high resolution, shock resistance, design and other advantages.