08/07/2006

The illumination for this NeoBulb Street Light is provided by its composite cluster of 18 LEDs light engines, and is capable of providing over 5,000 lumens output by pc-white NeoPac® Emitters.

NeoPac Lighting is demonstrating its leading outdoor LED technology at the 2nd China International LED Exposition in Beijing, taking place from Aug. 2 to 4.

“This marks our entry into the outdoor lighting market.  We have in planning whole series of LED products for outdoors.  Our NeoPac® Emitters and system-in-package light engines are the best approach for the requirements of ultra-high-power LED street lighting,” said Jeffrey Chen, president of NeoPac Lighting.

Chen assured that the NeoBulb Street Light can well control the LEDs junction temperature at under 60 °C, which had been lab measured and tested.

He went on to point out it is the best performing outdoor lighting device, packed with higher power and the highest lumen output among of the LED lamps currently available, thereby pushing LED general lighting to the highest level yet..

Outdoor Applications

The 135-watt NeoBulb Sreet Light is built with durable metal casing and sealed solid housing box. 

It has an IP rating of 65 for dust and water protection, and has been lab-tested to withstand natural weather - windy, rainy, high humidity, and sunny conditions. 

Chen explains, “It is a very difficult challenge to find good solutions to build an LED device with enough brightness lumen output for outdoor lighting.  There are technical barriers to overcome.  It was important to have protection from dust, water, and humidity, while able to efficiently conduct the generated heat away.”

The new NeoPac LED Street Light can have much commercial marketing applications, due to its energy efficiency, long life, stability, as well as the low maintenance cost of LED devices over conventional lighting fixtures,

It can be utilized for parking lots, yards and gardens, municipal roadways, street lamps, housing projects, public parks, and various other door settings with needs for high-brightness general illumination during the night time.

The demonstration model has a module dimension of 720 mm (L) x 450 mm (W) x 205mm (H), conforming to most dimensions of standard outdoor lighting fixtures in current use.

It is constructed with a base slot for mounting to lamp post of up to 10 meters in height.

Thermal Management

For such ultra-high-power outdoor lighting device, the most difficult challenge is in thermal management, according to Chen.

“It is important to keep all LED clusters at the same junction temperature, and at the 0 uniform rate of power dissipation.  To start with, the LEDs junction temperature must be kept low, and we have to eliminate the heat hot spots.  The LED clusters have to be maintained at the same temperature conditions and the same decay rate, so the brightness output stays uniform across”, as he explains.

The housing design for the NeoBulb Street Light is based on NeoPac light engine construction with its top-rated thermal management efficiency, with embedded heat pipes and a matrix of rectilinear metal fins to conduct the heat away from the front end out to the back side.

NeoBulb Universal Platform approach

Chen stresses that breakthrough and innovations in LED outdoor lighting can be successfully achieved through the single-system-package NeoBulb Universal Platform framework, with the basic building unit of NeoPac® Emitters and NeoPac® Light Engines.

He indicates that in order for other LED devices to offer enough brightness illumination for outdoor lighting, it is necessary to pack large number of LED clusters to provide large enough lumen output.

Chen states, “Based on current best LED efficiency available from other approaches, they would need about 125 LED light sources to achieve 5,000 lumens output.  For this large aggregate amount, there will be problems of power dissipation, heat management, and creating hot spots. This is virtually ‘Mission Impossible”.  They could not maintain the low and uniform junction temperature across the ultra-high-power LED clusters.  It can only be done through the approach of NeoBulb Universal Platform light engines.”

“To design a good functional LED street light with high enough lumen output, you must have excellent thermal management.  The system thermal resistance must be low.  For example, at NeoPac we can control junction temperature at 60 °C, with the ambient temperature at 25 °C.  With the difference at 35 °C, and at 125 watts, we are getting the system thermal resistance down to 0.26 °C / w, which is among the lowest in the industry.  Only our system approach can the decay loss be managed and the brightness output be maintained at a consistent and uniform rate”, he adds.

Size Constraints

In terms of technical and functional design, the demand for high-brightness lumen output and the amount of LED clusters also places constraints on the size of the final product.  

“For our NeoBulb LED Street Light, its dimension (720 mm x 450 mm x 205mm), it conforms to the current outdoor lighting fixtures.  When hang on a 12-meter lamp post on the highway, it is about the right size when looking at the ground level,” as Chen explains.

For other approach LED outdoor lighting without efficient heat management and control of junction temperature, they would need large amount of LED clusters, up to 100’s to reach the high illumination output of over 5,000 lumens.  However, the size of this device would be too large and too heavy to hang up on outdoor lamp posts. 

Overall, high-brightness outdoor lighting is one of the top targets for the industry, but Chen states that there are still some ways to arrive at the ideal goal.

Improved Brightness Output

He points out, “Right now with 5,000 lumens output, it is still not good enough for highway lighting at the 12-meter high level.  It needs to improve to higher brightness illumination.”

Chen stresses that NeoBulb Universal Platform has the best solution, “In effect, we are building the basis for the “Street Lighting Platform”.  We are setting the standard for LEDs outdoor applications.”

“The whole world is watching us now, because we are the pioneer in this field.  Within next year, we can achieve LEDs efficacy up to 75 lumens / watt.  Therefore NeoPac is able to offer ultra-high-power LEDs outdoor lighting with 10,000 lumens output in 2007.  This would be good enough, the high brightness requirement on outdoor illumination on all highways, city streets, and other public construction projects.” 

National Energy Programs

This will also mean great energy saving to replace all outdoor lighting fixtures with LEDs.  “We are taking the lead in the new technology revolution for ultra-high-power LEDs.  We are changing the way of outdoor lighting for the future,” Chen says.

Due to the high cost of oil and rising energy expenditures, all the industrialized economies in the world are enacting new national programs for energy saving and efficiency, including the promotion for solid-state lighting.

The U.S. has already kick-started its new “National Energy Policy”, signed into law by American president Bush in August of last year.  It has the stated goals of encouraging energy efficiency and conservation, promoting alternative and renewable energy sources, and also increasing efficiency of electrical appliances and commercial products.

Similarly, China also has a new national energy program.  The Chinese government aims to quadruple the national GDP from 2000 to 2020, with only a doubling of energy use, with the shifting to the use of clean fuels and energy efficiency in all sectors, which included the setting up of a national committee for Solid-State Lighting to promote the use of LEDs lighting devices, and development of solid-state lighting technology and industry in China. 

With the goal of reaching 10,000 lumens for outdoor illumination system, most of the public project construction and highway lighting can thus be replaced by LED street ghting. 

Chen predicts, “This will take place worldwide.  The NeoBulb Street Light is leading the way to replace outdoor lighting.  With our patented technology for thermal management and control the junction temperature at under 60 °C, NeoPac can reach the goal of high-brightness outdoor lighting.   There are many other systems in the market, but we have the true ultra-high-power “LED street lamp” to offer for the world.”