As a new type of light source, LED has attracted wide attention from energy saving, long life and no pollution. In particular, the Chinese Olympic Games successfully used a large number of LED technologies, and the results were extraordinary. Local governments have supported the LED industry and established a large number of LED demonstration units. At the same time, a large number of enterprises have also entered the field, and even the battery has become a famous BYD. The company once again raised the slogan of the LED world. Did the LED really enter a boom period?
Since no lighting device like LED has not yet matured, it has been highly anticipated, but the slow development has also made LED products too conceptual and lacking customer base. Even though the government is now trying to support the growth of LEDs with LED street lights as a breakthrough, LED customers are still not formed in civilian or commercial customers. At this time there is a dangerous signal: LED manufacturers have made compression cost the number one priority! Many companies have increased the LED current to reduce the number of wicks while maintaining the brightness to save costs, or to compress the PCB area, or It is a method to reduce safety devices, and of course everyone must believe in the inherent advantages of Chinese companies in terms of compression costs. Not to mention the impact of this on product safety issues. As far as the industrial cluster is concerned, LED has entered the price reshuffle situation without a market, which is unfavorable for the entire industry. Intensify the decline of SMEs.
This is a dangerous situation. On the one hand, the technological development of LEDs will be stagnant or even degraded. On the other hand, the compression of costs, or the excessive cost of attention, cannot guarantee the final product characteristics, and will not display LEDs to a large extent. Advantage. Therefore, I am daring to think that the LED industry development direction is wrong at this time.
In order to open the civilian market, the LED industry now designs LED luminaires in an alternative way, that is, directly replacing existing luminaires. However, in the process of lamp development, in addition to the direct replacement of incandescent lamps with compact lamps, there are few direct replacement modes. T8 and ceiling lamps are almost patents for fluorescent lamps, and chandeliers are still the world of tungsten lamps. Why are LEDs sure? Want to take the road of replacement?
What are the disadvantages of the existing replacement luminaire design?
Heat dissipation
The poor heat resistance of LEDs is well known and will inevitably lead to problems with the life of the wick. The design of existing LED lamps is often difficult to achieve heat dissipation. In a field where heat dissipation is very demanding, it uses very inferior passive heat dissipation methods, and most of them are air-cooled or even closed air-cooled. Like some luminaires, a plastic sleeve is added between the drive plate and the aluminum heat sink to increase the reliability of the insulation. It is also necessary to heat the silicone to improve the heat dissipation capability. The T8 lamp tube is still closed, and the wick can only rely on air convection heat transfer to the aluminum tube on the back of the lamp for heat dissipation. Generally, the internal temperature of such lamps will be seventy to eighty degrees. And if you take into account heat dissipation, weight is a problem; taking into account the weight, heat is difficult to guarantee, which is a dilemma in the existing design, there is no feasible standard.
2. Life expectancy
LED wick life decreases exponentially with increasing temperature; electrolytic capacitor temperature decreases by half for every ten degrees of increase; MOS temperature increases, internal resistance increases, loss increases, temperature increases (constant current mode), and eventually burns out . Of course, the domestic manufacturers did not give the life of the specific LED lamps. The propaganda only mentioned that the LED wicks lasted for 100,000 hours, but the LED life bottleneck was in the system driver board, and the LED wicks were not damaged, and the system driver had been hung up.
In addition, the light decay of LED is very serious, so the life of the luminaire should also take into account the visual experience, that is, how long after the brightness of the luminaire is reduced to a visually dark degree, it can be considered that the life is up, the customer will consider replacing the luminaire. This life is not given by the manufacturer (or no way to give it), but it is very important.
In addition, the existing LED household lighting is mostly limited by volume, and it is difficult to do very well in terms of protection. In areas with large voltage fluctuations and severe interference, the existing low-power design is a test.
The most important thing is, whether the life of LED is directly proportional to the life of the company. If the LED lamp for 10 years is broken, it will be broken in 2 years. If the company has closed down half a year ago, will the user take this risk?
3. Weight
In the spiral type of luminaire, the weight of the fluorescent lamp is only a fraction of that of the LED luminaire. Since there is no problem with the heat sink, the weight of the fluorescent lamp is negligible for the lamp holder, but the weight of the LED is a serious problem for the lamp holder. The test, especially the 7.8W screw interface LED lamp, its weight is very dangerous, which merchant has considered this?
4. Price
A typical LED driver board can last only 5 years (home) at 70 degrees Celsius, far from the "concept" of LED wicks for 10 years. Therefore, compared with fluorescent lamps of the same brightness, even if the fluorescent lamp has a life of only one year, the 1W1 fluorescent lamp is much more cost-effective than the 1W10 LED. Especially when the LED luminaire is damaged, the wick is not broken, but the whole lamp is replaced. One count is because one tenth of the drive board has to discard the remaining nine tenths of the lamp (the wick and the heat sink account for most of the cost of the entire lamp), if every manufacturer does not recycle it. Customers will not like such products.
5. Efficiency
Some people may be very surprised, LED is an energy-saving product, why should we consider the efficiency problem? I mentioned two points here, one is the PF value, and the other is the system efficiency. Since most of the existing LED designs are low-power, the passive PFC (filled valley) is used for the cost pressure. The PF may be up to 90, which is much smaller than the efficiency of the active PFC, and the LED is replaced by LED for the country. Fluorescent lamps that are very close in efficiency are a stress.
Since the existing designs of LED lamps (except street lamps) are mostly low-power, such as 4.8W, 7.2W, etc., the loss of the device accounts for a large proportion, and the isolation mode is inevitably low, in order to improve efficiency. The non-isolated method not only has to be well designed in terms of safety, but also has an efficiency of only about 80, which is not ideal. Moreover, the existing LED manufacturers in the end do not provide accurate values ​​of the LED illuminance, often the brightness is much smaller than the nominal value.
6. Light perception
Light perception is the visual perception of LED lighting by the human eye - visual perception. Because LED lights are a lighting product, their visual perception is very important. One advantage of LEDs is that the spectrum is pure, but this is a very serious disadvantage in terms of vision. The human eye can't observe a single-chromat light source for a long time, especially for infants and children in development. The pure cold white children's eye-protection lamp on the market is not suitable, even if it is not flashing. The full-spectrum incandescent lamp in warm tones is relatively suitable (using sunlight as a reference, it is undeniable that sunlight is the most needed for life) (If you have an understanding of LED plant growth lights, you should consider plant since Growth requires a modulated light source, which is more desirable for the human eye). Of course, LEDs can be modulated, but they are more troublesome, more professional, and require theoretical and a large amount of research data support. It is difficult for many homogeneous materials manufacturers or LED light source manufacturers or solution providers to achieve.
The LED is a point source, so the general LED luminaire has a relatively good graininess, and its illuminating position is relatively concentrated. There is a tingling sensation when visually illuminating the luminaire. This sensation usually only occurs with high power in other light sources. Therefore, the LED needs to be better designed on the uniform light to realize the expansion of the point source into a surface light source while ensuring the brightness, thereby improving the comfort of the eye.
Then there are many products that will do LED dimming design to save energy, not to mention the efficiency problem at low power. Due to the current in the coil, the gray scale change in the dimming design will be discontinuous. In the process of proportional adjustment, the brightness of the LED will gradually brighten and then suddenly become bright, the visual sense is very uncomfortable, and the dimming technology still needs to be developed.
From these aspects, the design of LED lamps requires further development.
What are the advantages of LEDs? In addition to high light efficiency, energy saving, and no pollution, there is a very special and often overlooked advantage - low voltage drive. The reason for this is that the LED can be used as a low-voltage safety lighting. The power supply and the wick, the high-voltage part will not be in direct contact with the user, and some safety problems will be avoided, for example, the existing lamp is damaged. The security issue that arises when replacing. However, many existing LED designs use a non-isolated mode to increase efficiency, making the lamp head still high pressure and very unsafe.
Compared with the existing LED home lighting power supply and wick design, I prefer the separate design of the switching power supply + constant current module + wick on the street light. The use of a switching power supply guarantees PF and efficiency, and can be easily done very well in terms of protection.
If all the 4.8W light sources are powered by a switching power supply, the PF and efficiency can be guaranteed during normal operation, even if the loss on the line is added (using the 1A current of Line 23, the loss is about 0.7W/10m) This is much lower than the loss of the existing design of 4.8W (0.3A14V, efficiency of about 80, loss of nearly 1.5W). Simply put, all the LED low-power lamps that can be used in the home use a switching power supply, and the low-voltage direct current is sent to the wick with copper wire. Even if the loss caused by the length of the wire is considered, it is far more than the existing one. Program economy.
If the heat dissipation design can be used on the CPU, the effect is absolutely satisfactory. It is necessary to know that the CPU is more sensitive to temperature than the LED wick. The cost of developing a heat sink mold for LED alone is a problem. It does not guarantee whether the company has professional qualification for heat dissipation design. The heat sink using CPU is relatively much better. Of course, the style is not so formal. There is a DIY model store on Taobao, and a 50WLED fan with a CPU.
In this way, the problems of efficiency and heat dissipation can be solved very well. Not only the life effect is solved, but also the replacement is very convenient. The LED wick is also working under a safe voltage, even if it is directly touched, it will not cause danger. Maybe a viable option?
LED is a light source that does not flash. In order to save energy, it has to be flashed. Although it is not good for the eyes, it is a drop of watermelon and sesame. I think that it is possible to use the ratio of 8421 to directly control how many lights are illuminated by the switch, but it is a good choice for dimming.
However, the current LED market, relying solely on replacement and imitation, cannot go out. The design of the power supply can be learned, and a certain solution can be adopted, but the replacement lamp can never occupy the mainstream market (unless there is a very advantage, whether it is light efficiency or price, this LED does not have). In the alternative design, LED has already reached the tip of the horn. In the case that the market has not yet been opened, the manufacturer has attributed the reason to the price factor and desperately compressed the cost. In fact, it is wrong. The fluorescent lamp is 20 yuan (compact, use MOSFET drive, T8 lamp about 4 yuan), and incandescent lamps of the same brightness as long as 8 angles, such a large price gap fluorescent lamps still occupy the mainstream market, because fluorescent lights are out of the same as incandescent lamps, more convenient, Unique structure, if the fluorescent lamp only thought of completely replacing the incandescent lamp, there is no U lamp, T8 and other lamp styles, I believe that the fluorescent lamp will still be a bleak operation. So LEDs don't depend on cost to survive, but a company that can have new LEDs to highlight its advantages. The company must understand the characteristics of LEDs and the needs of customers. Such companies are rare. In the current blind competition, many companies are swarming, all of them are the same architecture, the same appearance, how to design LED lamps, but few people really consider this.
Therefore, in this market state, the development of materials with higher transmittance and better uniform light effect may be a good choice for many companies.
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