Brief introduction to key technologies of high-efficiency metal-free heat sink LED lighting

　　LED lighting has the advantages of higher light efficiency, longer life, no harmful mercury, life span has almost nothing to do with the number of times the light is turned on and off, and people can "turn off the light at any time", and it can light up instantly. It is believed that it will eventually replace incandescent lamps and energy-saving lamps and become the mainstream of energy- saving lighting . In fact, LED lamps can only become the mainstream of general lighting when their cost-effectiveness exceeds that of incandescent lamps, especially the energy-saving lamps that are currently widely used.

　　The issue of LED lighting seems very clear, that is, the lighting efficiency needs to be greatly improved while ensuring the light quality, for example, more than twice that of energy-saving lamps; the price needs to be greatly reduced, preferably close to that of energy-saving lamps; making its cost performance significantly better than that of energy-saving lamps.

　　Most of the current LED general lighting lamps are composed of power LEDs, metal heat sinks and constant current drive circuits. The bulky metal heat sink not only increases the cost and weight of the lamp, but also consumes a lot of aluminum resources, which is contrary to environmental protection. An LED lamp is like a metal ball, which is not conducive to safety, especially high-power LED lamps. Therefore, many consumers still choose energy-saving lamps when purchasing.

　　This article will introduce a high photon extraction rate, high efficiency, and metal heat sink-free LED general lighting technology (LED lighting that can directly replace incandescent lamps and fluorescent energy-saving lamps with equivalent luminous flux) based on the research and development work of the author's company.

　　The luminous efficiency of the LED general lighting lamp is more than double that of the fluorescent energy-saving lamp; the color rendering index can be as high as 96; the LED general lighting lamp with a luminous flux of several tens to 1600 lm and higher can be manufactured, and the L70 life can reach 30,000 hours. It can directly replace 10-100W and higher power incandescent lamps and fluorescent energy-saving lamps with equivalent luminous flux.

　　1.  LED chip 4π light output, improve PN junction light extraction rate and actual light efficiency

　　The energy efficiency η of the white light LED luminescence process is:

　　η =ηI ×ηO × ηC ×K

　　Among them, ηI: internal quantum efficiency; ηO: external quantum efficiency; ηC: photon down-conversion loss; K: luminescent powder absorption.

　　Some people have analyzed that under ideal conditions [1], ηI = 0.95; ηO = 0.5; ηC = 0.875; K = 0.95, so the highest ideal energy efficiency η = 39.5%. The external quantum efficiency ηO here refers to the result of photons being absorbed by the chip, window material, phosphor and lens during the emission process, or reflected back to the chip at the interface of different refractive index media and then absorbed, that is, the light extraction rate of the LED component. If the optical power equivalent of 3500K warm white light is 320 lm/W, the highest light efficiency is 320×0.395=126 lm/W. This is obviously underestimated. But from this we can see that an important and huge potential factor in improving LED light efficiency is to improve the light extraction rate.

　　The light of LED comes from the PN junction of the LED chip. Its light is originally natural light that is uniformly emitted in all directions at a 4π solid angle, but currently almost all LED components emit light at ≤2π.

　　The application of LEDs has evolved from early indicator lights to digital displays and current large-screen color displays, backlighting for liquid crystal displays, etc. In these applications, the light originally emitted at 4π needs to be focused forward using reflective bowls and lenses, that is, converted into light emitted at ≤2π, including direct-insert, straw-hat, surface mount (SMD) and COB; such a transformation is necessary and correct for these applications.

　　However, such a transformation makes the light originally emitted backward by the chip gather forward, which will significantly reduce the extraction rate of light emitted by the PN junction, that is, reduce the actual effective light efficiency of the LED. This is not necessary for LED lighting that does not necessarily require ≤2π light output. If the LED chip is allowed to emit light at 4π, the extraction rate of photons generated by the LED PN junction can be significantly improved, that is, the actual light efficiency of the LED can be improved.

　　Figure 1 is a schematic diagram of light emission of a currently widely used SMD LED. The LED chip is mounted at the bottom of a light reflection bowl, and the reflection bowl contains a transparent medium with a flat or curved light emission surface (Figure 1 is a flat example).

　　Part of the 2π solid angle light (indicated by blue) emitted upward by the chip PN junction can be directly emitted from the light exit window, and the other part of the light is reflected by the reflection bowl after total reflection on the surface of the transparent medium or directly reflected by the reflection bowl before being emitted. Among them, the directly emitted light is about 2π[1-cos(sin-1(1/1.5)]/2π=25%. Here we assume that the refractive index of the transparent medium is 1.5, and the light emitted after reflection by the reflection bowl accounts for 75%. The reflectivity of the reflection bowl is 0.75. If the multiple reflections of the reflection bowl and the absorption loss of the transparent medium are ignored, the total light extraction rate is (25+75×0.75)%=81%.

　　The 2π light (indicated in red) emitted downward by the LED chip must undergo reflection from the chip's back-coated reflective film, the reflective bowl bottom, the reflective bowl wall, multiple reflections, and multiple absorptions from the bowl bottom and wall. The estimated output rate is about 60% (depending on the reflectivity of the reflective bowl wall and bottom, the electrode surface, the dielectric surface between the electrodes, the solid crystal adhesive, etc.).

　　Therefore, the total light extraction rate of the LED chip = (0.81 + 0.6) 2π / 4π = 71%, that is, about 30% of the light is absorbed by the LED element and converted into heat energy.

　　Figure 2 is a schematic diagram of 4π light emission of an LED chip, wherein the LED chip is a chip whose chip substrate is transparent, at least one series of chips connected in series or in series and parallel are fixed on a transparent substrate of an LED light-emitting element with transparent glue, and the chip is covered with a transparent medium layer or a luminescent powder glue layer.

　　If the chip substrate is sapphire, the epitaxial layer and PN junction on the sapphire are GaN, the P electrode is ITO, the transparent substrate of the LED element is glass, and the transparent medium is silica gel, their refractive indices are 1.77, 2.4, 1.8, 1.45, and 1.5 respectively. As can be seen from Figure 2, the light of each hemisphere 2π emitted upward and downward from the PN junction of the LED chip can be emitted smoothly, and there is basically no multiple reflection absorption inside the sapphire substrate. If the medium absorption is ignored, the light of the LED chip can be almost 100% emitted.

　　That is, the actual luminous efficiency of the 4π LED component is about (100-71)/71=41% higher than that of the SMD LED. Our experimental results are basically consistent with this.

　　It can be seen that making the LED chip emit light at 4π can increase the actual luminous efficiency of the LED component by about 40%, while reducing the heat generated by the LED. Considering the different structures of existing LED components, the luminous efficiency of 4π light should be more than 30% higher than that of ≤2π light.

　　In fact, almost all LED workers have known this concept for a long time, but it has not been put into practice. The key is that the heat dissipation problem of LED chips has not been solved.

　　2. Gas Heat Dissipation Analysis

　　To make the LED chip emit light at 4π, the chip must be surrounded by a transparent medium with high light transmittance and heat dissipation. People tend to think of using liquid to dissipate heat first, because the thermal conductivity of liquid in transparent media is generally much higher than that of gas. For example, the thermal conductivity of water is 0.5 W/(m·K), which is 20 times that of air, which is 0.025.

　　For more than ten years, people have been studying the use of liquid cooling to achieve 4π light output from LED chips, but there are still some difficulties that are difficult to overcome in liquid cooling. For example, the viscosity coefficient of liquid is much larger than that of gas. The viscosity coefficient of water is 8937μP, which is 10 times that of air and 77 times that of helium. The high viscosity coefficient makes it easy for the liquid around the LED chip to change phase and gasify due to the heat of the chip, and the generated gas is difficult to escape due to the high viscosity coefficient of the liquid. The chip is easily surrounded by static gas, and any static gas is a good insulator, so it is easy to overheat the chip and burn it. In addition, there are problems such as liquid easy electrolysis, corrosion of chips and luminescent materials, and pollution after the bulb shell is broken. So far, there is no good practical product.

　　Although gas has lower thermal conductivity than liquid, its viscosity coefficient is much smaller than liquid, so it is easy to form gas convection, which can effectively dissipate the heat generated by the LED when it is working, thereby achieving good heat dissipation effect.

　　In the early days, people installed LED chips on strip-shaped or flat transparent substrates, and operated them in the air, using air to dissipate heat. However, due to the low thermal conductivity and high viscosity of air, it is difficult to dissipate heat effectively. If the LED chip is installed on a flat plate, the heat concentration will be more unfavorable for heat dissipation, so it is difficult to make an LED lamp with high luminous efficiency and sufficient output luminous flux. For example, Ushio's LED filament lamp has an output luminous flux of only 36 lm and a luminous efficiency of only 60 lm/W[2]. Another example is Panasonic's LED chip installed on a transparent flat plate and air-cooled LED bulb, which has an output luminous flux of 210 lm and a luminous efficiency of 47 lm/W[3]. The luminous efficiency of these LED chips with 4π light output is actually lower than that of LED lamps made of existing LED components with ≤2π light output. The efficiency of existing A19-shaped bulbs with LED chips with a light output angle of ≤2π is 40 to 90 lm/W. The reason is that the problem of effective heat dissipation of the LED chip has not been solved, resulting in an increase in the PN junction temperature of the LED chip, low luminous efficiency, and low output luminous flux.

　　The company where I work has effectively solved the heat dissipation problem of 4π light-emitting chips [4]. The solution is: at least one string of LED chips with the same or different luminous colors is fixed on a transparent substrate strip with transparent glue, and the chips and the transparent substrate strip are surrounded by at least one layer of transparent glue or luminescent powder; the two ends of the transparent substrate have electrical lead wires to form an LED light strip (or LED filament); the LED light strip is installed in a vacuum-sealed transparent bulb, and the bulb is filled with a gas with high thermal conductivity and low viscosity coefficient that transfers heat and protects the LED; the LED electrode is led out through the lead wire of the core column of the vacuum-sealed bulb, and connected to an electrical connector through the LED driver . The electrical connector is used to connect to an external power source, so as to form an LED filament lamp with a similar appearance to an incandescent lamp, high light efficiency, and no metal heat sink, which can directly replace incandescent lamps and energy-saving lamps.

　　A19 LED bulbs with a luminous efficiency of up to 170 lm/W have been manufactured; their luminous flux can reach 760 lm; and their color rendering index (CRI) can reach 96. Recently, the company's laboratory has manufactured A19 lamps with a color temperature of 5000K, a CRI of 71, and a luminous efficiency of up to 193 lm/W. Their luminous efficiency is more than double that of energy-saving lamps. This has brought LED 4π light-emitting, metal-free heat sink LED bulbs into the era of practical use. Figure 3 is a schematic diagram of a LED filament lamp with four LED light strips connected in series.

　　Helium or a helium-hydrogen mixture is preferred as a gas with high thermal conductivity and low viscosity. The thermal conductivity of helium is 0.14 W/(m·K), which is 6 times that of air, and the viscosity is only 194μP[5], which is 1/8 of that of air. The thermal conductivity of hydrogen is 0.15, the viscosity is 87.6, and the cost is low, but the use is unsafe. To reduce the cost, a helium-hydrogen mixture can be used. A gas with high thermal conductivity and low viscosity can easily form effective convection heat dissipation, which can quickly take away the heat generated by the LED chip when it is working, transfer it to the bulb shell, and then dissipate it through the bulb shell to the surrounding air.

　　Secondly, a transparent substrate of the light strip with high thermal conductivity is used, such as hard glass, quartz glass, sapphire, transparent ceramic, AlN, etc. At the same time, a solid crystal glue and a luminescent powder glue with high thermal conductivity and high light transmittance should be used, and their thickness should be reduced as much as possible. The contact area between the transparent substrate and the luminescent powder glue and the heat dissipation gas should be increased as much as possible to reduce the thermal resistance from the PN junction of the LED to the heat dissipation gas. The at least one luminescent powder layer can be coated around the transparent substrate and the LED chip, for example, coated on both sides of the light strip with LED chips and without chips, or only on the side with chips. A luminescent powder layer can also be coated on the transparent substrate first, and the LED chip is fixed on the luminescent powder layer, and then a luminescent powder layer is coated after the chip is electrically connected.

　　In addition, the luminescent powder can also be coated on the inner wall of the lamp bubble shell. There is only a layer of transparent glue on the LED chip of the light strip, and the luminescent powder is away from the chip, which is beneficial to reduce light decay and increase the service life of the lamp.

　　We can use blue plus red or orange LED chips to improve CRI, and we can also use RBG three-primary color or multi-primary color LED chips to mix to make white light LED light strips without using luminescent powder. The chip can also be a chip substrate with a reflective film on the back or an opaque chip. The LED light strip made is still 4π light, but its light efficiency will be lower than that of a transparent chip substrate. The chip can also be a flip-chip LED chip, flip-chip on a transparent substrate with electrical connection lines printed on it to make a light strip. A high-voltage LED chip (HVLED) with multiple PN junctions on one chip can also be used to make a light strip to reduce the electrical connection lines between chips and improve the yield and production efficiency.

　　The luminous efficiency of this type of LED filament lamp is more than 30% higher than that of the existing bulb lamp made of LED components with light output of ≤2π. It also has no metal heat sink, which can save a lot of aluminum, is more environmentally friendly, and is lightweight. It has now begun to be accepted by the market and is being mass-produced.

　　However, some people are concerned that its service life is difficult to reach 30,000 hours or more, and it is difficult to produce high-power LED lamps with an output luminous flux of more than 800 lm. This will be discussed below.

　　3. Lifespan Analysis

　　The life of LED lamps mainly depends on the operating temperature of the LED PN junction and the light decay of the luminescent powder.

　　Figure 4 shows the luminous flux attenuation diagram of the commonly used GaN LED at different PN junction temperatures [6, 7], and the L70 life at different junction temperatures is marked in the figure. It can be seen from the figure that if the junction temperature is <85℃, the L70 life can reach more than 30,000 hours. The temperature of the LED PN junction is not easy to measure. The junction temperature of the PN junction can be estimated by using the displacement of the main wave peak, the change of the junction voltage, the infrared imager, the change of the luminous efficiency, etc.

　　Figure 5 shows the relationship between relative luminous flux and junction temperature [7]. As can be seen from Figure 5, under the condition of constant LED input power, the junction temperature is 75-85°C when the stable luminous flux decreases by 10% compared with the cold state luminous flux. The change of luminous flux under constant power conditions is the change of relative luminous efficacy. Therefore, we can measure the ratio of the initial luminous efficacy of the lamp to the stable luminous efficacy of the same input power after thermal stabilization to estimate the junction temperature of the PN junction when the LED lamp is working stably. If the ratio of this stable luminous efficacy to the initial luminous efficacy is ≥0.9, it can be seen from Figures 4 and 5 that the life of the lamp is estimated to be more than 30,000 hours. Of course, the light decay of the luminescent powder and other factors must also be taken into account; finally, it needs to be determined by actual measurement.

　　In other words, the design of LED filament lamps should meet the condition that the ratio of stable light efficiency to initial light efficiency is ≥ 0.9, so that the LED filament lamps can have a service life of more than 30,000 hours.

　　The experimental results of our life test are shown in Figure 6, which is the average value (Lr) of 14 400 lm LED filament lamp life tests with a ratio of stable light efficiency to initial light efficiency > 0.9. The dotted line in the figure is the light decay curve of the Energy Star 35,000-hour life, where 1,000 hours is defined as the initial value (100%). As can be seen from Figure 6, the L70 life of the LED filament lamp may reach more than 30,000 hours.

　　Now let's take a look at the importance of filling the bulb with high thermal conductivity and low viscosity gas. Figure 7 shows the change of the light efficiency over time of the same 3.9W LED filament lamp after it is filled with nearly one atmosphere of helium at room temperature and the exhaust pipe is broken and air is released under the same input power conditions. The upper curve in the figure is the test result of filling with helium, and the lower curve is the test result after air is released under the same test conditions. It can be seen from the figure that when filled with helium, the ratio of the stable light efficiency to the initial light efficiency is >0.9. Comparing Figures 4 and 5, the junction temperature of its PN junction is <85℃, and the expected life span can be greater than 30,000 hours.

　　However, once air is put into the lamp, not only the stable light efficiency is reduced by 19%, but also the ratio of the stable light efficiency to the initial light efficiency is reduced to <0.75. Compared with Figure 5, the junction temperature of the PN junction is >150℃! It is obviously difficult to work normally. Here we can clearly see the importance of filling with high thermal conductivity and low viscosity gas, which also explains why the LED filament lamp filled with air has low luminous efficiency and small luminous flux.

　　In addition, assuming that the life of an LED bulb is up to 30,000 hours, if it works for 3 hours a day, the purity of the gas in the bulb shell must be maintained during the working period of more than 20 years. The bulb shell must be vacuum sealed, and it is impossible to maintain the purity of the gas for a long time with existing organic or inorganic glue. Vacuum sealing can also completely isolate the influence of the surrounding environment on the LED components. The LED can work without the influence of water vapor, acid, sulfide, oxygen, PM2.5, etc. in the surrounding air, and it is more likely to have a service life of more than 20 years.

　　4. Analysis of Ceramic Tube LED Lamps

　　Previously, some people predicted that LED filament lamps could only produce low-power lamps below 500 lm. This prediction is not without reason, because the filament lamps assembled from LED filaments (light strips) are limited by the small contact area between the LED filaments and the heat dissipation gas, the small heat dissipation area, and the large thermal resistance, so the output luminous flux of a single lamp is indeed difficult to achieve >800 lm.

　　The goal of semiconductor lighting is to replace 10-150W general incandescent lamps and fluorescent energy-saving lamps with equivalent luminous flux. In fact, only in this way can semiconductor lighting become the mainstream of general lighting. Referring to the US Energy Star, the initial output luminous flux of 40W, 60W, 75W, 100W, and 150W incandescent lamps are 450, 800, 1100, 1600, and 2600 lm respectively.

How to make a high-power LED lighting lamp 　　without metal heat sink with a luminous flux of 800-2600 lm ? The key lies in: on the basis of maintaining the LED  4π light output, high efficiency and low heat generation, further increasing the heat dissipation area of ​​the LED, reducing the thermal resistance from the LED PN junction to the heat dissipation air around the lamp and further improving the heat dissipation capacity of the bulb.

　　The technical solution of RDS to solve this problem is [8]: directly attach the LED light strip or LED chip to the outer wall of a transparent tube with high thermal conductivity. The transparent tube can be, for example, a transparent ceramic tube, a quartz tube, a sapphire tube, etc. The transparent ceramic tube has a thermal conductivity of up to 23 W/(m·K) and a total light transmittance of more than 95%. Its thermal conductivity is close to that of the chip substrate sapphire. Its inner and outer surfaces are in contact with and dissipate heat from the heat dissipation gas, which greatly increases the heat dissipation area of ​​the LED and reduces the thermal resistance from the PN junction of the LED chip to the heat dissipation gas.

　　Figure 8 is a schematic diagram of an A19 LED bulb made of the above transparent ceramic tube LED light column. As shown in the figure, the LED light bar is fixed on the outer surface of a transparent ceramic tube, and a spring or bracket is provided at the upper end of the glass column on the bulb core column to fix the upper end of the ceramic tube. The lower end of the ceramic tube is connected and fixed to the lead wire of the core column, and the lead wire of the core column is connected to the output of the lamp driver, and the input of the driver is connected to the lamp holder, which is used to connect to an external power supply. When the external power supply is turned on, the LED lamp can be lit.

　　Figures 9 and 10 are cross-sectional schematic diagrams of two different structures of LED light-emitting columns. Figure 9 is a schematic diagram of an LED light-emitting column in which an LED light strip is attached to the outer surface of a transparent ceramic tube. Figure 10 is a schematic diagram of an LED light-emitting column in which an LED chip is directly bonded to a ceramic tube.

　　As shown in Figure 9, at least one LED light strip is fixed on the outer surface of the transparent ceramic tube with transparent glue, and the figure shows an example of four light strips. The transparent ceramic tube has a plane for installing the light strips, and the light strips are connected in series or in series and parallel.

　　Figure 10 shows an example of LED chips being directly fixed on a transparent ceramic tube. The LED chip is fixed on the plane of the ceramic tube pre-coated with a luminescent powder layer by transparent glue, or by a die-bonding glue mixed with luminescent powder.

　　FIG10 shows an example of an LED chip fixed on the first luminescent powder layer on the outer surface of a ceramic tube, and the LED chip is covered with a second luminescent powder layer. The LED chip is directly fixed on the high thermal conductivity ceramic tube through a thin luminescent powder layer, with no transparent substrate in between, only a thin layer of powder glue, and the sapphire substrate of the chip is basically in direct contact with the ceramic tube, with very low thermal resistance, which further reduces the thermal resistance between the PN junction of the LED and the heat dissipation gas, and can reduce the operating temperature of the PN junction, increase the operating current and power of the LED chip, and increase the output luminous flux. At the same time, medium-power LED chips with higher power can also be used to reduce the number of LED light strips and the number of LED chips, reduce the number of solid crystals and wire bonding, and improve production efficiency, yield rate and reliability. If necessary, double wire bonding can be used to further improve reliability.

　　As shown in FIGS. 9 and 10 , the light strips or chips are directly fixed on the high thermal conductivity tube, and each light strip and each chip can be kept at basically the same operating temperature, thereby reducing the probability of failure of the entire lamp due to excessive temperature rise of individual chips, thereby improving the reliability of the lamp.

The structure of the LED light-emitting column 　　shown in Figures 9 and 10 can also be transformed in many ways. For example, light strips with different structures can be used; the LED chip can be a chip with a back-coated reflective film or an opaque chip; the LED chip can use a blue plus red or orange LED chip to improve the CRI; the white light LED light-emitting column can also be made by mixing RGB three-primary color or multi-primary color LED chips without using luminescent powder; flip-chip LED chips can also be used; HVLED chips can also be used; the luminescent powder can also be coated on the inner wall of the bulb shell, etc.

　　The above method can effectively improve the lamp power and output luminous flux of a single lamp. However, the final heat dissipation of the whole lamp still depends on the heat exchange between the bulb and the surrounding air. The LED light column is located in the center of the bulb, and the contact area between the bulb and the surrounding air is limited. Even if a ceramic tube with a larger diameter is used, it is difficult to make an LED general lighting lamp with a larger output luminous flux.

　　5. Analysis of high power multi-tube lamps

　　Radixon has broken through the bottleneck with its multi-tube lamp solution[9], making it possible to realize LED lighting lamps with luminances of 800-1600 lm or higher without metal heat sinks. This type of multi-tube lamp is equivalent to splitting the bulb of a single lamp into several parts. There are gaps between the lamp tubes for air to flow freely, which makes it easy to form air convection, so that each lamp tube can effectively dissipate heat, greatly increasing the heat exchange and heat dissipation capacity between the lamp tube and the surrounding air, thereby increasing the lamp power and output luminous flux.

The heat dissipation scheme of multi-tube lamps can be called dual convection heat dissipation technology　　of gas convection heat dissipation in the tube and air convection heat dissipation between the tubes . It can produce LED general lighting lamps with small volume and higher output luminous flux without metal heat sink. At present, multi-tube ceramic tube LED lamps with luminous flux of 800-1600 lm and experimental sample lamps with luminous flux of up to 4000 lm have been developed.

　　Figure 11 shows an example of a 4-tube LED lamp with an output luminous flux of 1600 lm. Each tube is vacuum sealed and filled with a heat dissipation protective gas with high thermal conductivity and low viscosity coefficient. Each tube has a transparent ceramic tube LED light column. Each LED tube is driven by a constant current or current limit, which can avoid the problem of inconsistent light decay of each tube caused by positive feedback of LED current and temperature, ensuring consistent light decay and long service life of each tube.

　　Now we have made 2-tube, 3-tube and 4-tube T5 high-power LED lamps. The typical parameters of the multi-tube lamp with a color temperature of 5000K are:

　　2-tube lamp: 850lm, 6.4W, 133 lm/W, CRI:81; lamp height: 110mm, maximum diameter: 40mm, weight: 58g;

　　3-tube lamp: 1250lm, 9.3W, 134 lm/W, CRI:82; lamp height: 110mm, maximum diameter: 48mm, weight: 64g;

　　4-tube lamp: 1630lm, 12.2W, 134 lm/W, CRI:81; lamp height: 110mm, maximum diameter: 52mm, weight: 70g;

　　It can be seen that a 6.4W 2-tube lamp is equivalent to a 60W incandescent lamp; a 12.2W 4-tube lamp is equivalent to a 100W incandescent lamp. The overall lighting effect is above 130lm/W, without a metal heat sink, small in size and light in weight. The multi-tube lamp of Redison can easily be made into high-power LED lighting lamps of different powers by changing the number of tubes, the size of the tubes and the ceramic tubes.

　　VI. Conclusion

　　The luminous efficiency of LED chips with 4π light is more than 30% higher than that of existing LEDs with ≤2π light. Using high thermal conductivity and low viscosity gas to dissipate heat can make high-efficiency low-power LED filament lamps; using high thermal conductivity transparent tube LED light-emitting columns can further improve the heat dissipation capacity and make LED ceramic tube lamps with greater output luminous flux; using double gas convection heat dissipation technology, multi-tube LEDs can be made into LED general lighting lamps with luminous flux of 800-1600 lm and higher. Its overall luminous efficiency is more than double that of energy-saving lamps, there is no metal heat sink, low cost, light weight, long life, and it can replace 10-100W and higher power incandescent lamps and energy-saving lamps with equivalent luminous flux. It is a new generation of LED general lighting. Due to its high luminous efficiency, simple structure and low cost, it will help promote the advent of an era in which semiconductor lighting replaces incandescent lamps and energy-saving lamps and becomes the mainstream of general lighting.