LED lamp beads application and classification

　　What is LED :

　　LED is the abbreviation of light emitting diode. Its basic structure is a piece of electroluminescent semiconductor material placed on a rack with leads, which is then sealed with epoxy resin on all sides. It can emit light normally when a suitable voltage is applied.

　　Common knowledge about the size of LED chips :

　　According to the appearance, chips are generally divided into round chips and square chips. Round chips are relatively low-end and their performance is not stable enough. I generally do not use LEDs produced by round chips; square chips are generally measured by size, such as 12mil (1mil = 0.0254 square millimeters). Generally speaking, for chips of the same brand, the larger the chip size, the higher the brightness. The LED lamp beads I most commonly use are generally 9~12mil for red and yellow light, and 12~14mil for white, blue, and green light. This is also the most commonly used chip on the market. If a larger chip is used, the brightness can be greatly improved, but the chip price will increase significantly. This is why large-size chips are rarely used.

　　LED color knowledge:

　　The different colors of LEDs are determined by chips with different wavelengths. For example, the general wavelength of red light chips is 620~630nm (nanometers), the general wavelength of green light chips is 527nm, the general wavelength of blue light chips is 470nm, and the general wavelength of yellow light chips is 585nm.  White light LEDs also use blue light chips, but adding an appropriate amount of phosphor to the blue light chip will emit white light.

　　LED classification:

　　According to the power: can be divided into low power, high power (in the industry, lights above 0.5W are generally called high power lights)

　　According to the appearance: it can be divided into direct plug-in type and surface mount type.

　　Straw hat LED: It can be subdivided into F3 (the diameter of the lamp head is 3mm) and F5 (the diameter of the lamp head is 5mm) according to the size of the lamp head; or it can be subdivided into rimless, thin-rimmed, thick-rimmed, and round-headed according to the shape of the lamp head; it can be divided into transparent and foggy according to whether the lamp head is transparent or not.

　　Piranha LED: It can also be divided into F3 and F5 according to the size of the lamp head, and can be divided into round head (the most common piranha lamp) and flat head (this type of head is very special, with a light-emitting angle close to 180 degrees, and is generally used in situations where diffuse light is required) according to the shape of the lamp head.

　　Low-power SMD LED: According to the appearance size, it can be divided into 0805, 1206, 3020, 3528, 5050 or 5060 (the difference between 5050 and 5060 is very small, and it is difficult to distinguish them with the naked eye. For less professional customers, you can call them according to their habits).

　　High-power LED :Generally classified by power, the common ones are 0.5W, 1W, 3W, 5W, 8W...

　　Common knowledge about the number of LED chips:

　　The same LED lamp most often uses only one chip, but in special cases, two or even four chips can be used. For example, a straw hat lamp can use one or two chips (considering its small size, inconvenient heat dissipation leads to unstable performance, generally only one or two chips are used); a piranha lamp can use one, two, three, or four chips, and I most often use one and two chips; SMD 3528 lamps can use one, two, or three chips (our company often uses one or two chips), and SMD 5050/5060 generally uses three chips. Special note: When SMD lamps use three chips, there are two situations:

　　1. The colors of the three chips are exactly the same

　　2. The three chips are red, green and blue, which is what we often call RGB lights.

　　Common knowledge about LED viewing angle:

　　The most common light-emitting angle of direct-plug LEDs is 120 degrees, and special ones can be 45 degrees or 15 degrees.

　　LED voltage common sense:

　　The voltage required for a single low-power LED lamp varies with color. Red/yellow: generally 1.8~2.1 volts, white/green/blue: generally 3.0~3.6 volts. The voltage required for a 1W high-power lamp is the same as above.

　　Common knowledge about LED current:

　　1. For low-power LED lamps (including plug-in or SMD), the current allowed to pass through each chip should generally not exceed 20 mA; the current allowed to pass through each dual-chip lamp should generally not exceed 40 mA; similarly, the current allowed to pass through each three-chip lamp should not exceed 60 mA.

　　2. High-power LEDs, I usually use 1W, which allow a maximum current of 150 mA.

　　Common knowledge about LED brightness (intensity):

　　1. Definition of Candela, International Candela, and Candela

　　Under standard atmospheric pressure of 101325 Newtons per square meter, an absolute "black body" (i.e. an ideal object that can absorb all external light without any reflection) with an area equal to 1/60 square centimeter, at the solidification temperature of pure platinum (Pt) (about 2042K or 1769℃), has a luminous intensity of 1 candela in the vertical direction. In addition, the concepts of candlelight, international candlelight, and candela are different and should not be equated. In terms of quantity, 60 candela is equal to 58.8 international candlelight, and 1 candela of a Hefner lamp is equal to 0.885 international candlelight or 0.919 candela.

　　2. Luminous intensity and brightness

　　Luminous intensity is referred to as light intensity, and its international unit is candela, abbreviated as cd. Lcd refers to the luminous flux emitted by a light source within a unit solid angle in a specified direction. When the radiation of the light source is uniform, the light intensity is I=F/Ω, Ω is the solid angle, the unit is steradian (sr), F is the luminous flux, the unit is lumen, and for point light sources, I=F/4. Brightness indicates the brightness of the luminous surface, which refers to the ratio of the luminous intensity of the luminous surface in a specified direction to the area of ​​the luminous surface in a vertical and specified direction, and the unit is candela/square meter. For a diffuse scattering surface, although the light intensity and luminous flux in each direction are different, the brightness in each direction is equal. The fluorescent screen of a TV is similar to such a diffuse scattering surface, so when you watch the image from all directions, you will have the same sense of brightness.

　　3. mcd value

　　Mcd value is an informal term in the industry. Different manufacturers use different test instruments to measure the same product, and the mcd value is different. In the actual sales process, the two most common concepts are lumen and brightness (mcd) value. As a salesperson, you don't have to fully understand the technical aspects, but you need to keep in mind the mcd value of our conventional low-power LED lights (subject to the parameters listed in the quotation).

　　LED color temperature (color temperature) common sense:

　　Color temperature is the most common indicator of the quality of the light source spectrum. Color temperature is defined by an absolute black body. When the radiation of a light source in the visible region is exactly the same as that of an absolute black body, the temperature of the black body is called the color temperature of the light source. The characteristic of a low color temperature light source is that in the energy distribution, red radiation is relatively more, usually called "warm light"; when the color temperature increases, the proportion of blue radiation in the energy distribution increases, usually called "cold light". The color temperatures of some commonly used light sources are: standard candlelight is 1930K (Kelvin temperature unit); tungsten filament lamp is 2760-2900K; fluorescent lamp is 3000K; flash is 3800K; noon sunlight is 5400K; electronic flash is 6000K; blue sky is 12000-18000K. Generally defined, warm white temperature: 2700-3200K, pure white: 4000-4500K, daylight white: 6000-6500K, cool white: above 6500K

　　T8 lamp (LED) is equivalent to ordinary fluorescent lamp

　　6w 15w

　　8w 20w

　　9w 25w

　　15w 30w

　　18w 35w

　　20w 40w

　　LED bulb is equivalent to ordinary incandescent lamp

　　1w 10w

　　3w 25w

　　5w 40w
 
　　7w 60w

　　LED spotlights        are equivalent to ordinary incandescent lamps

　　3w 25w

　　5w 40w

　　7w 60w

　　12w 90w

　　What are the advantages of LED light sources

　　As a light-emitting device, LED has attracted much attention because it has advantages over other light-emitting devices. In summary, LED has the following advantages:

　　(1) Long service life: LED, as a conductor solid-state light-emitting device, has a longer service life than other light-emitting devices. Its brightness half-life can usually reach 100,000 hours. If LED is used to replace traditional car lights, its service life will be much longer than the life of the car itself, and it has the characteristic of not needing to be repaired or replaced throughout its life.

　　(2) Low power consumption: LED is a low-voltage working device, so at the same brightness, it consumes the least power, which can greatly reduce energy consumption. On the contrary, with the development of technology and materials in the future, it will have higher luminous efficiency. People have calculated that if all lighting fixtures in Japan are replaced by LEDs, two large power plants can be reduced, which is very beneficial to environmental protection.

　　(3) Fast response time: LEDs can generally respond within tens of milliseconds (ns), so they are high-speed devices, which is far beyond the reach of other light sources. Using LEDs to make high-mounted brake lights for cars greatly improves the safety of cars at high speeds.

　　(4) Small size, light weight, and impact resistance: These are the inherent characteristics of semiconductor solid state devices. Color LEDs can be used to produce various clear and exquisite display devices.

　　(5) Easy to adjust light, adjust color, and controllable: LED, as a light-emitting device, can control brightness by changing the current flowing through it, and can also change and adjust color by configuring LEDs with different wavelengths. Therefore, light sources or display screens composed of LEDs can be easily controlled by electronics to meet the needs of various applications, and have no difficulty in compatibility with IC computers. In addition, the application of LED light sources is not limited by the principle, and it is highly plastic and can be extended arbitrarily to achieve building block assembly. At present, LED is the only large-screen color display screen.

　　(6) LED light sources do not contain environmental pollutants such as mercury and lead, and will not pollute the environment. Therefore, it is well deserved that people call LED light sources "green" light sources.