作者：Blade

Expression of the LED industry-entanglement and nothing

entanglement

In early 2012, When you go to Hong Kong exhibitors, a 3W LED bulb called the price of 20 yuan, which will make the site once sensation, but now the lowest 3W bulb reach to single digits. In 2012, the price war in the LED industry is entangled, to low prices or keep price, it is difficult to avoid the problem.

Equally tangled problem is LED technology advances and new generation of products speeding quickly. The lack of a unified and standard LED products quality standard system, and thus on the market, there are quite a mixed bag, inevitably bad money drives out good money.

Expression of the LED industry-entanglement and nothing

For prices downturn, the industry believes that at First, the global economic downturn. It is very unfavorable for the domestic LED enterprises rely mainly on export earnings; Second, the imbalance between supply and demand, the lack of demand, especially in the domestic market and in the low end products get together, it is too homogenization, so companies only enter into a price war. The result of the price war, it also means that the the industry reshuffle remodeling will be inevitable.

Nothing

In 2012, the leading traditional lighting companies once again be pushed to the cusp, the reason is not because of its large-scale transition to the LED industry, they are nothing out of the chaos of the senior management disputes, the situation is like watching the TV series, the dramatics person are like fighting, an outsider stunned, it can not help but secretly sigh, how does the leading enterprises? The operation and management of private enterprises in China must be hidden all the “clouds”? Or all a myth will have a day to burst?

On May 25, 2012, NVC announced said Wu Changjiang, resigned chairman, executive director and chief executive officer, and all his posts for personal reasons. Since then, the occurrence of disputes between NVC large shareholders Wu Chang jiang and Yan Yan; On September 4, civil unrest subsided, Wu Changjiang return to NVC; Currently, Wu Changjiang, SAIF, Schneider are the NVC’s three shareholders, Three Musketeers, and they finally shake hands.

Logically, the traditional lighting companies experienced market baptismin, and to have today’s fame and status, but what we worried about is that whether fragile management system, can really afford the heavy responsibility of leading Chinese lighting industry transition to the LED industry? The leading lighting big enterprises, are you okay?

The current status of LED stage lighting applications

LED has features of high luminous efficiency, dimmable, small monomer power, high selling prices. As technology advances, LED stage lighting applications has been widely used.

 

LED has features of high luminous efficiency, dimmable, small monomer power, high selling prices.

 

Since the promotion of blue-ray, white-ray and high-brightness LEDs in 1990s, the luminous efficiency of LEDs improved continuously. The luminous efficiency of commercialized LED tubes has reached up to 50lm/W – 100lm/W. And it is still increasing with time. It is estimated that the maximum luminous efficiency can reach up to 200lm/W at last, far more than 10lm/W – 30lm/W of incandescent bulbs (including halogen lamps) and other exceeding light sources. But single LED chip has small power, only 1W – 5W. The maximum output luminance can only be a few hundred lumens. While stage lighting applications usually require a luminous flux of tens of thousands lumens. Previously, LED designers and engineers never think of using LED lighting products on stages.

 

In the beginning of this century, blue-ray LEDs has been popularized and white-ray LED lighting technology has been mature gradually. The luminous efficiency of LED lamps exponentially increased. At the same time, it also has advantages of prompt respond and simple dimming method. Combing multiple LED lamps as single LED stage lighting applications with output luminance quickly became the favorite way to stage lighting designers. At first, due to some technical reasons and the expensive price, these lamps received very little notice. Recently, with the popularity of further improved luminous efficiency, condenser cups, internal dies, housing and other parts, many manufacturers started to assemble the production by themselves.

 

There are two LED white-ray lighting modes: blue-ray dies with phosphors, some part of blue-rays will be converted into yellow light through phosphors. Yellow rays combine with blue rays can generate white rays; another method is grouped red-ray LEDs, green-ray LEDs and blue-ray LEDs together to create white rays. The former is typically used in LED display applications. The later is typically used in LED stage lighting applications. Compared LED lamps with incandescent bulbs, the current luminous efficiency of the former is two times of the later. Secondly, thanks to the small size and low temperature characteristics of LEDs, optical designs with higher luminous efficiency make the whole luminous flux of LED stage lighting applications several times higher than that of incandescent stage lighting applications. Combined these two factors, same luminous flux, incandescent lamps consumed far more power than LED lamps does. Thus low-powered LED lamps still can meet the light intensity requirements of stages.

U.S. scientists invested warm white LED lamp

It is well known that LED (light0emitting diode) energy-saving lights have higher luminous efficiency and longer service life. The current LED lights are mainly used blue-ray LED chips as light sources, which hindered their popularity in the field of indoor lighting applications, since almost all residential lighting applications are warm white. Scientists from the University of Georgia, USA has recently developed the world’s first warm white LED lamp with single phosphor and single light-emitting unit in the world. Detailed information about this material has been published in the latest “Nature”.

 

It is well known that LED (light0emitting diode) energy-saving lights have higher luminous efficiency and longer service life.

 

As the paper’s lead author, Mr. Zhengwei Pan, associate professor at the University of Georgia, indicated that: currently, white-ray LED lamps are generally used as flashers and headlights (used in vehicles). But the emitted blue rays are less likeable, especially in indoor lighting applications. Our materials can successfully create a type of warm white light, and meanwhile achieve a realistic color reproduction. The previous improved LED lamp with single phosphor had failed to achieve such effect.

 

There are two main indicators to measure the quality of artificial light. Correlated color temperature is used to measure the well-being of the light. Take indoor lighting for example, color temperature lower than 4000K is an ideal correlated color temperature. Color reduction degree is another important indicator, naming the ability of the light source to simulate natural light. An ideal indoor lighting source should have a color reduction degree no less than 80. Distortion will occur when the color reduction degree below this value. The new developed materials meet these two conditions together: with correlated color temperature less than 4000K and color reduction degree higher than 85.

 

The general working principle of warm white LED lamp is coating phosphor with different colors on blue-ray LED chips to let them generate warm white rays. This is a type of phosphor-based white-ray LED lights. However, mixing these materials at a precise ratio needs a lot efforts and money. And the ultimate light color will have differences, since various materials has various responds to temperature changes.

 

Although the research result has huge market prospects, there are still remained several problems to be solved to have this type of material to be used in houses, schools and offices. The luminous efficiency of this new material is still much lower than white-ray LED light sources. In addition, the large-scale production will also face up with many challenges.

More than 80% failure of LED products is from LED power suppliers

LED lighting market is fast growing, along with the rapid development of LED lighting industry. On one side, manufacturers for traditional light power supplies aggressively introduced new LED power suppliers or upgraded products for LED lights. On the other side, man entrepreneurial companies have been founded as well. However, the power technology is not mature yet. There is still no unified standard and the corresponding market is also in chaos. Relevant experts believe that LED lighting market will be finally dominated by a few giants. Marketing strategy an product quality is the key to the final victory.

 

More than 80% failure of LED products is from LED power suppliers

 

2012 is a mixed story for LED lighting industry. Market is growing fast. But not every participants earned money at last. Most of LED street light suppliers did not make any profits. Most of LED tunnel suppliers only earned enough money to cover all charges. Some LED commercial lighting application providers with strong trade ability actually made money. All LED chip makers and packaging factories, both domestic and overseas earned money in 2012.

 

It is noticed that most manufacturers for LED power suppliers also had a good harvest in 2012. LED power suppliers are technically belong to the traditional electronics industry. Chinese manufacturers have strong manufacturing capabilities in this area. Although it is an emerging industry, price war has started in advance, especially in low-powered LED driver field. In fact, the price of small-powered LED drivers is very transparent, normally 24-25 yuan.

 

But LED drivers are still a highly profitable business. The relatively high technical threshold and large capital investment are major reasons. In addition, High-powered LED drivers are usually used in high-powered LED lighting applications, such like LED street lights, LED tunnel lights. These lamps are mainly used in government lighting projects and supported by government policies. Manufacturers will use best components and modules on their products to obtain a good effect, which will virtually increase the production cost at last.

 

According to incomplete statistics, about 80% failure of LED lighting products comes from LED power supplies. In recent years, with the continuous improvement of packaging technology and cooling technology, the stability of LED drivers has reached a satisfied level. The additional light attenuation and color shift all comes from the unreasonable cooling design.

The cooling section design for outdoor LED lights

Outdoor LED lights usually work in harsh and complex working environments: temperature, ultraviolet rays, humidity, rain, dust, chemical gases and other climate factors. All these factors combined can significantly affect the light attenuation of LED chips. Designers should take all these environmental factors into account when during the design of outdoor LED lights.

 

Outdoor LED lights usually work in harsh and complex working environments: temperature, ultraviolet rays, humidity, rain, dust, chemical gases and other climate factors.

 

Shell and radiator designed as a whole to solve the LED cooling problem is an appropriate method. Normally, LED manufacturers prefer to use aluminum or aluminum alloy, copper or copper alloy and other alloys that with good thermal conductivity.

 

Radiator is a crucial part of LED lamps. The shape, size, heat dissipation surface area of it must be well designed. Small radiator will make the lamp work in high temperatures, affect the luminous efficiency and life time. Large radiator need to use a lot of materials, increase the cost and weight, declining the product competitiveness. Appropriate LED radiator design is essential. Radiator design has the following parts:

  1. Make clear of the cooling power that LED lights need.
  2. Some parameters that radiator design needed: specific heat of the metal, thermal conductivity of the metal, chi resistance, thermal resistance of heat sinks, thermal resistance of ambient air.
  3. Heat dissipation type: air convection radiator, strong wind cooling section, heat pipe, as well as other heat radiation ways. From the cost comparisons: air convection radiator cost least. Heat pipe and cooling jet cost the most.
  4. Make sure the maximum operating temperature (ambient temperature plus the permitted temperature rise)
  5. Calculate the volume of the cooling area. Determine the shape of radiator.
  6. Combine LED lamp body and radiator to a complete lighting fixture. Take simple indoor lighting tests: more than 8 hours constant work; at room temperature: 39℃–40℃. Calculate the average working temperature, see if it meets the cooling requirements. If normal condition is not met, related parameters are necessarily to be reset.
  7. Radiators and lampshades should be waterproof, dustproof. Rubber pad / rubber mat can be used between lampshade and radiator to prevent aging. Stainless steel bolts are used as waterproof / dustproof devices. By above four points, and plus related regulations for outdoor lighting applications and roadway lighting standards. All these are basic knowledge that outdoor lighting designers must be obtained.

Light attenuation solutions for LED roadway lighting products

In order to solve the serious light attenuation problem of LED roadway lighting products, LED street light manufacturers need to start with basic materials, solving the cooling problem from inside. For example, when light-emitting components stick with aluminum plates, heat conducting glue plays a rather important role. Some makers believe that heat conducting films and heat conducting pads have much better performance, the thicker the better. However, they do not take into account of the thermal resistance. In addition, heat conducting films or soft heat conducting pads actually cannot really fit the substrate surface. There are many pores, which is another form of thermal resistor. Under the interference of so many resistances, the heat conduction efficiency has been virtually reduced.

 

n order to solve the serious light attenuation problem of LED roadway lighting products,

 

It does not mean that LED makers should find other materials to take place of heat conducting glue. In fact, heat conducting glue is still the most suitable material in LED package. Right glue may have quite low thermal resistance, such like screen printed soft ceramic heat conducting glue (SPSCHCG), which is quite different from traditional paste-fit heat conducting glues. SPSCHCG is a type of soft semi-liquid material. When coat this material up on the aluminum plates, heat conducting particles will penetrate into the pores of the substrate surface and fill them to full to form a completely flat plane. Therefore the thermal resistance can be reduced to a minimum level, and the heat generated by LED roadway lighting products can be quickly conducted outwards. In addition, due to the good ductility of SPSCHCG, this material can expand and contract along with aluminum plates in the high temperature of baking and reflow. The stress is very small, will not cause a warp or burst of aluminum plates.

 

With the continuous improvement of packaging technology, carrier board design and cooing module structure, the production costs of LED roadway lighting products are also further reduced. But only a few Chinese manufacturers spent energy and money on the research and development of materials. In issues of solving technical problems and reducing costs, they are more in favor of purchasing. In this part, manufacturers from North America and Japan have much better performances. They are more like to find breakthroughs on basic materials, reducing production costs by innovations.

Analysis of the light attenuation of LED roadway lighting applications

Currently, the majority of LED roadway lighting applications face with serious light attenuation. This problem can only be fundamentally solved through the improvement of LED cooling technology. According to recent statistics, China has the highest growth rate in LED roadway lighting applications. It is predict that this dominating will be continued in 2013 in the global market. In 2012, the Chinese Ministry of Science and Technology issued a LED-lighting-related project: “Ten thousand lights in ten cities”. Although this implementation is a economic model that create the market demand via central government policies, but the response is not as good as expected.

 

Analysis of the light attenuation of LED roadway lighting applications

 

Lacking of unified LED standard is not the only reason for the huge gap between the market and policies, serious light attenuation of LED roadway lighting applications is another potential problem for this issue. The former unified standard will be possible programmed in the near future, while light attenuation problem still need to be solved via the improvement of cooling technology.

 

Temperature is the major element to accelerate the light attenuation. As a type of high-powered LED lighting applications, LED roadway lamps usually work in high temperatures. LED street lights have relatively high working temperatures than ordinary residential lamps. Thus LED manufacturers paid a large amount of energy and money on the development and design of heat dissipation substrates, sinks and other cooling models. After package, makers need to take painting process to keep cooling models away from climate erosion. Unexpectedly, the external protection seal back the heat generated by LED lamps, speeding up the light attenuation of them.

 

The heat generated by LED chips / LED light sources are a type of small ranged concentrated thermal energy. For high-powered LED roadway lighting applications, the high input power and the high interface temperature are also heat sources with lamp bodies. Working in high temperatures for a long time, if cooling models cannot effectively conduct all heat outwards, not only the service life and performances of LED lights will be affected, but also the light attenuation will be more serious. LED street lights are normally used outdoors, taken into account of the climate factor, most of manufacturers added anodized shell protections or spray paint on the surface of lamp bodies, which is definitely block the heat dissipation.

LED test: errors frequently happened

Usually, in LED test, luminous flux, CRI, color temperature and power deviation are four major aspects that with relatively high failure rates. Unqualified quality testing results mainly concentrate in four aspects: 1. Electrical insulation cannot meet the corresponding requirements: insufficient internal clearance and creepage distance, with touchable conductors (not safely isolated). Especially for some small sized LED lamps, the compact structure forced manufacturers to ignore the requirements of electrical insulation. 2. Using drivers that cannot meet the safety requirements of LED power supplies, or using simple buck circuit to drive LED lamps. 3. Electromagnetic disturbance voltage exceeds standards: most of LED drivers use cheap but weak circuits without any anti-electromagnetic measures, leading to conduction voltage and radiation exceeding. 4. Cannot meet the light and color performance requirements. LED light-emitting principles have huge differences with traditional lighting technologies. Many designers only concerned about whether their products can send out light normally, but ignore the quality of photometric and colorimetric requirements, resulting in the huge differences in color temperature deviation and low CRI.

 

Usually, in LED test, luminous flux, CRI, color temperature and power deviation are four major aspects that with relatively high failure rates.

 

In LED test, lamps from one manufacturer may get different testing results in different testing processes. There are three main reasons that cause to such situation:

 

1)       Testing system errors. This error is within the allowable range. Due to production process deviations, it is very hard for different testing system to stay exactly the same. There must be some errors. Traditional light fitting with error less than 1.5% are qualified. However, tests for LED lighting products have not been standardized. The permissible error range of LED lighting products is relatively vague, generally between 3% and 5%.

 

2)       Error comes from different testing environment. Lamps’ working environment along with the different surface contamination will exert huge influence on testing results, 7%-8% error. Especially for some products which used light-emitting surfaces as the secondary optical lens. These products have concave and convex structures. Dust and dirt can easily accumulate on the surface, hardly to clean up, which seriously affect the luminous flux and furthermore the light distribution.

 

3)       Errors come from equipment deviations and standard errors. Normal LED test includes: spherical integral devices, devices for light distribution measurement and equipments for light radiation. Spherical integral devices are used to measure the luminous flux of LED lights.

Advantages and selections of LED ceiling light

LED ceiling light use special process and G24 LED light source package, with higher luminous efficiency (120lm/W), better cooling effects, lower light attenuation (less than 3% after 3000-hour aging test), longer service life, safer, more durable and more reliable. LED ceiling light can be used in various conditions. Working temperature: -20 centigrade to 55 centigrade; working voltage: 12VDC/24VDC, 100-240VAC; Color: Cool White / Warm White / Natural White / Red / Yellow / Green / Blue / Multiple colors.

 

ED ceiling light use special process and LED light source package, with higher luminous efficiency (120lm/W),

 

Compared with traditional ceiling lamps, LED ceiling mounted lights are more advanced in: 1. Energy-saving; the power consumption of white-ray LED ceiling lamps is only 1/10 of incandescent lights and 1/4 of energy-saving lights, with the same output luminance. 2. Longer service life; the average lifetime of LED ceiling lamps can reach up to 100,000 hours, very suitable for residential applications; 3. Frequent turning on/off the power will cause damages to energy-saving lights. But this condition will not occur on LED lights. Due to their special working principles, all of LED-related lighting devices can work under high frequency. 4. LEDs are a type of cold light source, using solid package, easy to transport and install, can be embedded within small and closed equipments, with low heat generation.

 

How to choose suitable LED ceiling light? Are there any knacks?

Radiator: how fast a lamp can outwardly transfer the heat generated by LED chips determine the light attenuation speed and the service life of LED lights. Working in high temperatures for a long time will speed up the light attenuation of LED chips. Main cooling methods for LED ceiling lights are mainstream integral heat sink, single cooling column for single lamp bead, external fan cooling mode. The size of radiator along with the quality of aluminum material affect the heat dissipation and also selling prices.

 

Lamp drivers / power supplies: in fact, the lifetime of power supplies usually determine the lifetime of the entire lamp. For the reason that, compared with LED chips, power supplies are more likely to fail. Normally, LED chips can have a working life of 50,000 hours. The lifetime of most power supplies is far less than this value. electronic components, circuit designs and other factors together determine the power factor, power efficiency, reliability, temperature rise and lifetime of LED power supplies.

LED test: sampling test results are not optimistic

From the current LED product structure and developing direction, the main testing standards for LED-related lighting products are focus on optical performance, electrical performance, terminal conductivity, radiation safety and service life. Optical performance is mainly related to the luminous flux, radiant flux, luminous efficiency, chromaticity coordinates, correlated color temperature (CCT), color rendering index (CRI). Photoelectric detection, light distribution detection, light energy detection, attenuation and anti-vibration test are five major normal testing for G24 LED lighting products.

 

From the current LED product structure and developing direction, the main testing standards for LED-related lighting products are focus on optical performance, electrical performance, terminal conductivity, radiation safety and service life.

 

However, according to a recent sampling LED test report, results are not satisfied. Recently, the Guangdong Provincial Bureau of Quality Supervision issued a product quality supervision and inspection testing report for self-ballasted LED lighting products. The final results showed that among 23 self-ballasted LED lamps, 17 are unqualified. The failure rate is as high as 73.9%. Failure items include accidental contact with live parts, the wet processing insulation resistance and dielectric strength, mechanical strength, fault status, chromatically tolerances, general CRI, harassment voltage, lamp power, heat resistance, interchangeability, power factor, the initial light efficiency / luminous flux, anti-blame capability and so on.

 

Awful LED test results happened frequently in recent years. Tracing the source, lacking of standards and immature testing systems mainly contribute to the high failure rate of LED sampling tests.

 

Although routine performance tests need to be taken before products leaving factories, not all manufacturers will follow testing standards strictly. On one hand, the majority of LED manufacturers do not have complete testing equipments. On the other hand, they need to take cost into account. Current large LED enterprises have nationally recognized LED test laboratories and relatively complete testing equipments. SMEs usually conduct several small simple LED tests (maybe a few hours), also lacking of necessary testing equipments. These phenomena led to the high failure testing rate mentioned previously and consequently a great deal of negative impact in the LED lighting market.

 

CRI should be greater than 80, otherwise the initial luminous efficiency cannot meet the requirements of energy efficiency to reach the energy-saving effect. Currently, some LED suppliers blindly pursue high luminous efficiency but ignore the light attenuation and total lifetime of their products, leading to the low service life of LED lighting products and the high failure rate.