High-power LED lamp parameters and design techniques

　　LED lamp bead parameter introduction:

　　1. Brightness

　　LEDs have different brightness and different prices.

　　Lamp cup: general brightness is 60-70lm;

　　Bulb: general brightness is 80-90lm.

　　Note: 1W brightness is 60-110lm, 3W brightness can reach up to 240lm, 5W-300W is an integrated chip, packaged in series/parallel, mainly depending on the current, voltage, and number of strings and parallels.

　　1W red light, the brightness is generally 30-40lm; 1W green light, the brightness is generally 60-80lm; 1W yellow light, the brightness is generally 30-50lm; 1W blue light, the brightness is generally 20-30lm.

　　LED lens : Primary lenses are generally made of PMMA, PC, optical glass, silicone (soft silicone, hard silicone), etc. The larger the angle, the higher the light efficiency. With a small-angle LED lens, the light will be emitted farther.

　　2. Antistatic ability

　　LEDs with strong antistatic ability have long life and are therefore expensive. Usually, only LEDs with antistatic ability greater than 700V can be used in LED lighting .

　　3. Wavelength

　　LEDs with consistent wavelengths have consistent colors. If you require consistent colors, the price will be high. It is difficult for manufacturers without LED spectrophotometers to produce products with pure colors.

　　White light is divided into warm color (color temperature 2700-4000K), pure white (color temperature 5500-6000K), and cold white (color temperature above 7000K). Europeans prefer warm white.

　　Red light: Band 600-680, of which 620 and 630 are mainly used for stage lights, and 690 is close to infrared

　　Blue light: Band 430-480, of which 460 and 465 are more commonly used in stage lights.

　　Green light: band 500-580, of which 525 and 530 are more commonly used in stage lights.

　　4. Leakage current

　　LED is a unidirectional conductive light source. If there is a reverse current, it is called leakage. LEDs with large leakage current have short life and low price.

　　5. Lighting Angle

　　LEDs with different uses have different light-emitting angles. Special light-emitting angles have higher prices.

　　6. Lifespan

　　The key to different quality is lifespan, which is determined by light decay. Small light decay means long lifespan, while long lifespan means high price.

　　7. LED chips

　　The light source of LED is chip. Different chips have different prices. Chips from Japan and the United States are more expensive. LEDs from Taiwanese and Chinese manufacturers are more expensive.

　　Chip prices are lower than those in Japan and the United States.

　　8. Chip size

　　The size of the chip is expressed by the side length, and the chip size is generally:

　　38-45mΩ, large chip LEDs are better quality than small chips. The price is proportional to the chip size.

　　9. Colloid

　　The colloid of ordinary LEDs is generally epoxy resin. LEDs with anti-UV and fire retardants are more expensive. High-quality outdoor LED lighting should be anti-UV and fireproof.

　　10. Color rendering value

　　Pure white: 60-65, warm white: 50-60. Since different companies use different packaged phosphors , the color rendering values ​​are also different.

　　Point light source design tips

　　Each product has a different design, and different designs are suitable for different purposes. The reliability design of LED lighting includes: electrical safety, fire safety, applicable environmental safety, mechanical safety, health safety, safe use time and other factors. From the perspective of electrical safety, it should comply with relevant international and national standards. Since LED is a new product, China's national standards lag behind, but the country provides product qualification tests. LED lighting with international safety certification (such as GS, CE, UL, etc.) and national product quality certificates are more expensive because these products are reliable in safety design. Consumers should pay attention to carefully identifying the authenticity of the certificate. There are not many manufacturers with international safety certification and national product certificates.

　　From the health aspect, products designed with non-toxic materials are more expensive, especially indoor LED lighting. Don't be greedy for cheap LED lighting with odor. Currently, only a few LED manufacturers use non-toxic materials. You can distinguish them directly with your nose. Products with odor are much cheaper than those without odor. Toxins such as lead, mercury, and cadmium need to be analyzed by professionals.

　　From the perspective of environmental safety, LED products with reliable dust and moisture-proof design, fire-proof materials, UV protection, and low-temperature cracking resistance are more expensive. The technical parameters of LEDs mainly include luminous intensity, chromaticity, wavelength, color temperature, etc. Below we give a brief introduction to these parameters.

　　Luminous Intensity (IV)

　　Light intensity is defined as the luminous flux emitted per unit solid angle, with the unit being candela (cd). Generally speaking, a light source will emit its luminous flux in different directions with different intensities. The intensity of visible light radiation emitted per unit solid angle in a specific direction is called light intensity.

　　Chromaticity

　　The human eye's perception of color is a complex process. In order to quantify the description of color, the International Commission on Illumination (CIE) records the visual sensation caused by the human eye to radiant energy of different wavelengths based on the visual experiment of the standard observer, and calculates the color matching function of the three primary colors of red, green and blue. After mathematical conversion, the so-called CIE1931ColorMatchingFunction(x((),y((),z(()) is obtained. Based on this color matching function, several color measurement definitions were subsequently developed, allowing people to describe and use color. According to the CIE1931 color matching function, the stimulus value of the human eye to visible light is expressed as XYZ, and the x, y values, namely the CIE1931 (x, y) chromaticity coordinates, are converted by the following formula. Through this unified standard, the description of color can be quantified and controlled.

　　x,y: CIE1931 chromaticity coordinates (ChromaticityCoordinates)

　　However, since the color gamut constructed by (x, y) chromaticity coordinates is non-uniform, it is difficult to quantify color differences. Therefore, in 1976, CIE converted the CIE1931 chromaticity coordinates to make the color gamut it formed a color space close to uniform, so that color differences can be quantified. That is, CIE1976 UCS (Uniform Chromaticity Scale)

　　Chromaticity coordinates, represented by (u', v'), are calculated as follows: Dominant wavelength (λD) is also one of the methods for expressing color. After obtaining the chromaticity coordinates (x, y) of the device under test, mark them on the CIE chromaticity coordinate diagram (as shown below), connect the chromaticity point of the E light source (chromaticity coordinates (x, y) = (0.333, 0.333)) with the point and extend the connection line. The wavelength value where this extended line intersects with the spectrum trajectory (horseshoe) is called the dominant wavelength of the device under test.

　　However, it should be noted that under this marking method, the same dominant wavelength will represent multiple different chromaticity points, so it is more meaningful when the chromaticity point of the device under test is close to the spectral trajectory. However, the color characteristics of white light LEDs cannot be described in this way.

　　Purity

　　It is an auxiliary representation when describing color with dominant wavelength. It is defined as the linear distance between the chromaticity coordinates of the DUT and the chromaticity coordinates of the E light source and the spectral trajectory from the E light source to the dominant wavelength of the DUT.