The LED lens is closely linked with the LED to enhance the light use efficiency and luminous efficiency. It can be used according to different effects. Different lenses change the optical system of the LED's light field distribution. The specifications are transmissive and reflective.
Ⅰ. Material type of high-power LED lamp bead lens
1. High-power LED lamp beads silicone lens
a. Because of the high temperature resistance of silica gel (reflow soldering is also possible), it is often used to directly encapsulate the LED chip.
b. Generally, the size of silica gel lens is small, with a diameter of 3-10mm.
2. High-power LED lamp beads 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 or extrusion); high light transmittance (the transmittance is about 93% when the thickness is 3mm); disadvantages: the temperature cannot exceed 80° (heat distortion temperature 92 degrees) ).
3. High-power LED lamp beads PC lens
a. Optical grade Polycarbonate (PC for short) polycarbonate.
b. Plastic materials, advantages: high production efficiency (can be completed by injection molding and extrusion); light transmittance is slightly lower (the transmittance rate is about 89% when the thickness is 3mm); disadvantages: the temperature cannot exceed 110° (heat distortion temperature 135 degree).
4. High-power LED lamp bead glass lens
Optical glass materials, advantages: high light transmittance (97%), high temperature resistance, etc.; disadvantages: single shape, fragile, difficult to achieve mass production, low production efficiency, high cost, etc. However, at present, very few domestic manufacturers have begun to develop glass molding technology, using mold fusion casting to produce glass lenses, which can produce lenses with various shapes and special surfaces. In addition, mold production has good product consistency and high precision, and can greatly improve production efficiency and effectively reduce the cost of glass lenses. With the characteristics of high light transmittance, glass lenses are bound to become optical plastic high-power LEDs. Alternative products for lenses. However, the current high price of such production equipment makes it difficult to popularize in the short term. In addition, the shortcomings of glass that are more fragile than PMMA and PC materials require more research and exploration. In terms of the improved technology that can be achieved now, the non-fragile characteristics of glass can only be improved by coating or tempering, although these treatments , The light transmittance of the glass lens will be reduced, but it will still be far greater than the light transmittance of ordinary optical plastic lenses. Therefore, the prospect of glass lenses will be broader.
Ⅱ. Application classification of high-power LED lamp bead lens
1. A lens
a. The primary lens is directly encapsulated (or glued) on the LED chip holder and integrated with the LED.
b. The LED chip (chip) theoretically emits 360 degrees, but in fact the chip can be fixed and packaged on the LED bracket, so the maximum light-emitting angle of the chip is 180 degrees (more than 180 degrees, there is a small amount of afterglow), and the chip There will also be some stray light, so that through a lens, all the light of the chip can be effectively collected and different light angles such as 180°, 160°, 140°, 120°, 90°, 60°, etc. can be obtained, but different There is a certain difference in the light-emitting efficiency of the light-emitting angle LED (the general rule is: the greater the angle, the higher the efficiency).
c. The primary lens generally uses PMMA, PC, optical glass, silica gel and other materials.
2. High-power LED lamp bead secondary lens
a. The secondary lens and the LED are two independent objects, but they are indeed inseparable in application.
b. The function of the secondary lens is to converge the light-emitting angle of the LED light source to any desired angle between 5° and 160°. The distribution of the light field can be mainly divided into: circle, ellipse, and rectangle.
c. The secondary lens material generally uses optical grade PMMA or PC; currently, glass is only selected under special circumstances. However, with the promotion and popularization of glass molding technology, the secondary lens will usher in a material revolution, and optical glass will replace optical grade PMMA or PC.
Ⅲ, high-power LED lamp bead lens specification classification
1. Through type (convex lens)
a. When the LED light passes through a curved surface of the lens (double convex has 2 curved surfaces), the light will be refracted and concentrated, and when the distance between the lens and the LED is adjusted, the angle will also change (the angle is inversely proportional to the distance). The optically designed lens spot will be very uniform, but due to the limitation of the lens diameter and lens mode, the light utilization rate of the LED is not high and the edge of the spot has a relatively obvious yellow edge (the reasons for the yellow edge will not be repeated for the time being);
b. Generally used in large-angle (above 50°) spotlights, such as table lamps, bar lamps and other indoor lighting fixtures;
2. Catadioptric type (cone type or cup type)
a. The design of the lens uses a penetrating condensing light in the front, and the tapered surface can collect and reflect all the side light, and the overlap of these two kinds of light (the same angle) can get the most perfect light utilization With beautiful light spot effect;
b. Some changes can also be made on the surface of the cone lens, which can be designed into a mirror surface, a frosted surface, a bead surface, a striped surface, a threaded surface, convex or concave surface, etc. to obtain different spot effects.
3. Lens module
a. It is to complete a whole multi-lens lens through injection molding of multiple single lenses. According to different needs, it can be designed into a 3-in-1, 5-in-1 or even dozens of in-one lens modules; two separate lenses can also be passed through The brackets are combined together.
b. This design effectively saves production costs, realizes the consistency of product quality, saves space in the lighting mechanism, and is easier to achieve "high power" features.
Ⅳ. Design and mold processing of high-power LED lamp bead lens
1. First of all depends on the light source (high-power LED lamp beads), different brands of high-power LED lamp beads (such as CREE, LUMILEDS, Seoul, Osram, Everlight, Edison, Changsenyuan, etc.), its chip structure and packaging There will be differences in methods, light characteristics, etc., resulting in differences when the same lens is matched with different specifications and brand LEDs; therefore, targeted development (oriented by mainstream brands) is required to achieve the actual desired effect;
2. Use optical design software (such as Code V, ZEMAX, TracePro, ASAP, LighTools, etc.) and mechanical modeling software (such as: Pro/E, UG, SOLIDWORKS, etc.) for design and optical simulation, and continuously optimize to obtain the corresponding optical lens
3. The LED lens itself is a precision optical accessory, so it has extremely high requirements on the accuracy of the mold, especially the processing accuracy of the lens optical curved surface must reach 0.1μm. Generally, the following equipment is required for the processing of such high-precision molds: ultra-precision processing machine (such as PRECITECH NANOFORM 350), CNC integrated processing machine, precision grinder, precision milling machine, drilling machine, CNC precision spark machine, surface profiler, interferometer Wait.
4. The most precise part of the mold is the optical mold core. First, a special mold core steel (such as Swedish S136 mirror steel) must be selected and heat treated to 55° to complete the rough embryo. After nickel plating on the rough embryo, use ultra-precision It is obtained by processing a curved surface by a processing machine.
Ⅴ. Material and production of high-power LED lamp bead lens
1. As an optical-grade product, LED lenses have strict requirements on light transmittance, thermal stability, density, refractive index uniformity, refractive index stability, water absorption, turbidity, and maximum long-term working temperature. Therefore, the material of the lens must be selected according to the actual situation. In principle, choose optical-grade PMMA, if you have special requirements, you can choose optical-grade PC. At present, the PMMA material of Mitsubishi is the best (VH001 is the frequently selected grade), and Nantong Liyang, the branch of Mitsubishi in China, is slightly inferior;
2. It must be equipped with a dust-free workshop with a level of 10,000 or higher. The operators must wear anti-static clothing, finger cots, and masks, and other anti-static and dust-proof measures, and the workshop should be inspected and cleaned regularly.
3. It is necessary to have professional optical injection molding machines such as Toshiba, Demag, Haitian, Chen Hsong and other brands, and strictly control the injection molding process to obtain qualified products.
4. Product inspection: no bubbles, no dents, no sink marks, no flow lines, no crescents; shape accuracy Rt<0.005 surface roughness Ra<0.0002.
5. The product must be packaged in anti-static and dust-proof PVC, and must be completely sealed. The temperature and humidity must be strictly controlled for storage, and it is best not to store it for more than one year.
The advantages of led lens are as follows
1. No matter the distance, the lampshade (reflector) is not much different from the lens. In terms of uniformity, the lens will be better than the reflector;
2. Use a small-angle LED lens, the effect is better than the lampshade, because it needs to be shot far! The lampshade has been condensed through the lens (because the LED itself must have a lens) and then pass through the mask to condense the light, this time will waste a lot For light, it is better to condense the light in the lens, and the light-emitting angle of the lens is easy to handle!
Another: if the space is available, using three 1W, the effect is much better than using one 3W!
3. In contrast, the lampshade has a wide range of uniform points, but the projection is not good, and the lens is the opposite;
4. The LED penetration is more high-end.
