How to improve the luminous efficiency of LED lights

I. Introduction

Early in August 2012, CREE Company released a LED bulb whose whole lighting effect was over 170lm / W of in the United States, power was 7.3W, while the luminous flux was up to 1250lm. What can be said for the LED luminous flux is that there is no maximum but only higher.

For LED applications-oriented enterprises, how to enhance the luminous efficiency of LED products is our long-term research topics and direction.

For enterprises, improving the luminous efficiency of LED products will be imperative. Current LED products include indoor LED bulb, LED candle lights, LED spotlights, LED tube light, LED down lights, LED ceiling light, LED panel lights and mining lights, outdoor lighting mainly include LED high bay lights, LED tunnel light and LED flood light.

In the future, what we urgent to do is that use public appearance to manufacture superior products. The “superior” is nothing more than performance and light effects.

Second, methods of how to improve the light efficiency of LED products

We take the 18W LED tube light for example on how to improve the optical efficiency.

2.1, the technical indicators of LED tube light

the main technical indicators of 18W LED tube light are as follows:

Requirements at the lowest cost to achieve maximum light efficiency. Based on these indicators, depend on the following aspects to improve light efficiency.

2.2, LED tube light design

The rated of the 2835 LED used is 0.2W, maximum luminous flux is up to 26lm. Theoretical luminous efficiency is over 130lm / W.

The main technical indicators are as follows:

By integrating sphere, the LED is tested in the case of different current driving, the optical parameters of the LED as follows:

Test results can be seen from the above, LED light efficiency decreases as the current increases.

Suppose we adopt 50mA current to drive, then the power of the LED is 0.149W when the current is 50mA. Let power efficiency at 88%, 85% light shade.

First calculate LED Power:

18.5W × 0.88 = 16.28W

Taking into account the actual power of the LED,converted LED quantity:

16.28W ÷ 0.149W / teeth = 110

Total luminous flux of LED:

110 × 20lm / pcs = 2200lm luminous efficiency of the system:

2200lm × 0.85 ÷ 18.5W = 101 lm / W

Therefore, theoretically calculated, only 110 2835, to meet the requirements.

The actual test results as shown below:

The actual results of the luminous efficiency is lower than the theoretical efficiency, the LED due to the internal material absorption of the light inside the tube, and loss after multiple reflections of light, the system will be lower than the theoretical optical efficiency values,which need to be further adjusted ??according to the actual test results.

2.3, adopt high luminous flux or luminous efficiency of the LED

According to the previous theoretical calculations and actual test results, the light loss rate is about:

(2200 × 0.85-1711) ÷ 2200 × 0.85 = 8.5%

That utilization efficiency of the light is 91.5%.

If using the same drive current that is 50mA, the luminous flux of the LED is 22lm, ceteris paribus, the last of the luminous flux and luminous efficiency:

Total luminous flux of LED:

110 × 22lm / pcs = 2420lm

Luminous efficiency of the system:

2420lm × 0.915 × 0.85 ÷ 17.9W = 105 lm / W

At this time,the loss of the spectrophotometer and other factors have been considered the asubstantially consistent with the actual test.

2.4, increasing the number of LED

in the case of can not be used higher luminous flux of the LED, we can use increase the number of LED to improve efficiency.

under the same drive current of the power, LED quantity is increased, the power is constant, single LED drive current is reduces, LED luminous flux is increased, LED luminous efficiency is increased.

If the LED number is increased to 132, the drive current is constant, power LED is constant and single LED power is:

16.28W ÷ 132 = 0.123W

Correspondence table can be seen, the drive current of single LED is about 42mA, the single flux is 17.5lm.

The total flux is:

132 × 17.5lm / pcs = 2310lm

Luminous efficiency of the system:

2310lm × 0.915 × 0.85 ÷ 17.9W = 100.36 lm / W

The actual test results is the same as the calculation results.

2.5, improve power conversion efficiency

The power parameters are unchanged, but conversion efficiency is increased, the lamp power is reduced, other optical parameters are not changed.

Such as the power efficiency is increased, to 92% ,the luminous flux is constant, the whole lamp power:

17.9W × 0.88 ÷ 0.92 = 17.1W

Luminous efficiency of the system:

2200lm × 0.915 × 0.85 ÷ 17.1W = 100 lm / W

2.6,adopt high transmittance lens or through the mask

The light transmittance of the translucent cover of the LED tube light is only 85%, if use higher transmittance through the mask, such as 90% light transmittance through the mask, the lamp of the light flux will be greatly increased.

Luminous efficiency of the system:

2200lm × 0.915 × 0.9 ÷ 17.9W = 101.2 lm / W

We can see improve the efficiency of the light shade, we can achieve the same purpose of improving light efficiency.

2.7, increasing reflective film

Affixed reflective film inside the bulb, and its main purpose is to reduce absorption of the light inside the lamp and increase the light. The actual test result shows that the whole effect of the LED tube light posted the reflective film increase 5 lm / W on the basis of the original . Thus also achieve that luminous efficiency is 100lm / W.

2.8, adjust the distance between the LED and transparent cover

The closer the distance between the mask and LED is , the greater LED energy is, the more light penetrating through the mask is,the whole effect of light is relatively high.

But for some applications where there is a need to consider the effect of lighting applications. Such as tube lamps, the LED is too close to the transparent mask, the internal LED light spot maybe can be seen when is lighted up,which is not very good to the application of the results

2.9, handle LED cooling

The following diagram is the graph of the LED junction temperature and flux output. As can be seen from the graph, along with the LED junction temperature is increased, LED’s luminous flux is reduced, and the power is essentially the same, so that the light efficiency is reduced.

Therefore, to obtain a higher light efficiency, ensuring LED heat is also an important factors. Typically, LED related parameters given by LED packaging manufacturers are obtained in the under the conditions that LED junction temperature is 25 ?, and we use the LED in the daily time, LED’s actual junction temperature is in the 70-80 or so. That is, when we use the LED, the effective luminous flux is only about 90% of the calibration. Third, the conclusion

3.1 Costing

For more than a few programs to improve light efficiency, cost accounting is as follows:

[Note] as the main material above cost price, excluding aluminum plate, labor and processing fees.

Apparently, in all scenarios, the cost of increasing the number of the additional LED is the highest, while t the increased costs of using the reflective film is the least.

3.2 Conclusion

Results can be seen from the above analysis, although increasing the light efficiency of the LED tube light as the ultimate goal can be achieved in many ways. Each method has its own advantages and disadvantages, this is not setting them.

For businesses, to achieve cost reduction and efficiency ,what the feasible and best solution is that spent the lowest cost to achieve the best lighting.

To sum up, the LED light efficiency improvement, the cost, performance, lighting design need to be taken into account, selecting the most cost effective solution to achieve the best product designs.

We have studied how to improve the light efficiency of the LED light,then I will tell you what the application of it.Nowadays,the LED flood light and LED tube light is most widely used as the representatives of the home lighting and decorative lighting in daily life,the LED tube light enjoys a great popularity in our corridor, restaurants, shopping, leisure and entertainment, galleries, exhibition halls and other indoor environments everywhere, the LED flood light is mainly used in city squares, parks, stadiums, the facades of large commercial buildings and hotel, stage, waiting rooms, airports etc. where need higher brightness lighting to illuminate, Lead Lighting adopts high brightness SMD as the light source of the LED tube and highly integrated and high brightness COB as the light source of the LED flood light, which fully guaranteed stability and soft light of the LED tube light and octahedron breadth and brightness irradiation range of the LED flood light, while LED tube light and LED flood light use low voltage constant current driver, which current the alternating into direct current so that improve energy efficiency and reduce the waste heat energy and stroboscopic effect excite the human eye, the most important is that the LED lighting without adding mercury and other heavy metals harmful to our body and pollution the environment, that’s why the LED light is famous for energy-saving and environmental protection ,login http://www.ledclan.com to learn more features and uses of the LED tube light and surf www.lead-lighting.com to know more anosome LED floodlights and other LED lighting.

Related Articles - LED bulb, LED flood light, Luminous efficiency, LED tube light, LED panel, luminous flux, conversion efficiency, United States, outdoor lighting, Total,

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