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LED lenses are generally silicone lenses, because silicone is resistant to high temperatures (and can also be reflowed), so it is usually packaged directly on the LED chip . Generally, the silicone lens is small in volume and has a diameter of 3-10 mm. The led lens is generally closely associated with the LED, and it helps to improve the light extraction efficiency of the LED and the optical system in which the lens changes the light field distribution of the LED.
The LED lens is an optical system that is closely associated with the LED and contributes to improving the light extraction efficiency of the LED and changing the light field distribution of the LED. The high-power LED lens/reflector is mainly used for collecting and guiding light of high-power LED cold light source products. The high-power LED lens designs the light distribution curve according to the angle of the different LEDs, and increases the optical reflection to reduce the light loss and improve the light efficiency (and the set aspherical optical lens). The following focuses on the secondary concentrating high power LED lens of PMMA material.
Second, by material classification
1, silicone lens
a. Because silicone is resistant to high temperatures (and can also be reflowed), it is usually packaged directly on the LED chip.
b. The general silicone lens is small in volume and has a diameter of 3-10mm.
2, PMMA lens
a, optical grade PMMA (polymethyl methacrylate, commonly known as: acrylic).
b, plastic materials, advantages: high production efficiency (can be completed by injection molding, extrusion); high transmittance (93% penetration rate at 3mm thickness); disadvantages: temperature can not exceed 80 ° (heat deformation temperature 92 degrees ).
3, PC lens
a, optical grade material Polycarbonate (referred to as PC) polycarbonate.
b. Plastic materials, advantages: high production efficiency (can be completed by injection molding, extrusion); light transmittance is slightly lower (the penetration rate is about 89% at 3mm thickness); disadvantage: the temperature cannot exceed 110° (heat distortion temperature 135) degree).
4, glass lens optical glass material, advantages: high transmittance (97% penetration rate at 3mm thickness), high temperature resistance; disadvantages: large volume, heavy weight, single shape, fragile, mass production is difficult to achieve, production Low efficiency, high cost, etc. However, the current price of such production equipment is high and it is difficult to popularize in the short term. In addition, the disadvantages of glass compared to PMMA and PC materials are more fragile, and more research and exploration are needed. In the improved process that can be realized now, the non-fragile properties of the glass can only be improved by coating or tempering treatment, although after these treatments The transmittance of the glass lens will be reduced, but it will still be much larger than that of the ordinary optical plastic lens. So the prospect of glass lenses will be even broader.
Third, the application classification of LED lenses
1. Primary lens
a. The primary lens is directly encapsulated (or bonded) on the LED chip holder and integrated with the LED.
b, LED chip (chip) theoretically emits 360 degrees, but in fact the chip is placed on the LED bracket to be fixed and packaged, so the maximum illumination angle of the chip is 180 degrees (more than 180 ° range also has a small amount of residual light), another chip There will also be some stray light, so that all the light of the chip can be effectively concentrated by one lens and different light angles such as 180°, 160°, 140°, 120°, 90°, 60°, etc., but different There is a certain difference in the light extraction efficiency of the LED at the exit angle (the general rule is: the greater the angle, the higher the efficiency).
c. The primary lens is generally made of PMMA, PC, optical glass, silica gel, etc.
2, secondary lens
a. The secondary lens and the LED are two separate objects, but they are inseparable when applied.
b. The function of the secondary lens is to converge the illumination angle of the LED light source again to any desired angle between 5° and 160°. The distribution of the light field can be mainly divided into: circular, elliptical and rectangular.
c. The secondary lens material is generally optical grade PMMA or PC; in special cases, glass can be selected.
Fourth, by specification
1. Transmissive (convex lens)
a. When the LED light passes through a curved surface of the lens (double convex has a curved surface), the light will refract and condense, and the angle will change when the distance between the lens and the LED is adjusted (the angle is inversely proportional to the distance). The lens spot of the optical design will be very uniform, but due to the limitation of the lens diameter and the lens mode, the light utilization efficiency of the LED is not high and the edge of the spot has a relatively obvious yellow edge;
b. Generally used for concentrating light at large angles (above 50°), such as table lamps, bar lights and other indoor lighting fixtures;
2, catadioptric (cone or cup type)
a. The design of the lens is concentrating in front of the concentrating light, and the tapered surface can collect and reflect all the side light, and the overlap of the two kinds of light (the same angle) can obtain the most perfect light utilization. Beautiful spot effect;
b. It is also possible to make some changes on the surface of the conical lens, which can be designed as a mirror surface, a frosted surface, a bead surface, a stripe surface, a thread surface, a convex surface or a concave surface to obtain different spot effects.
3, lens module
a, is to complete a single multi-head lens by injection molding a plurality of single lenses, which can be designed into 3, 1, 5 or even dozens of lens modules according to different requirements; or two separate lenses Combined by brackets.
b. This design effectively saves production costs, achieves consistency of product quality, saves space in the lighting mechanism, and makes it easier to achieve "high power" and other characteristics.
First, the lens basic concept lens is made according to the law of light refraction. A lens is an optical component made of a transparent substance such as glass, crystal, or the like. The lens is a refractor whose refractive surface is two spherical surfaces (part of the spherical surface), or a spherical surface (part of the spherical surface) of a flat transparent body. It has a real image and a virtual image. Lenses can generally be divided into two broad categories: convex lenses and concave lenses. The central part is thicker than the edge part, which is called a convex lens, which has three kinds of convex, convex, convex and concave; the central part is thinner than the edge part, which is called concave lens, flat concave, convex and concave.