High Bright LED Market Overview and Forecast for 2010

Classification of LED by means of Drive Current
20mA is Low power
50-150mA is Medium power
150-1000mA is High Power

The most promising LED growth is the LED for lighting that as CAGR growth of 42% and Mobile application is 35% from 1998-2008

HBLED Market growth is of 2009 is 6.2 times of 1998, with total revenue of exceeding $5,000M in 2008.

Technologic advancement was prominent in year 2000 to 2009, especial the year 2005-2009, a lot of LED has great improved efficacy.

The 100Lm/watt Cool White LED and 80Lm/W warm white LED can be made in volume commercially in 2008. HBLED market continues to grown 11% from 2007 to 2008 to a $5.1B.

Mobile Phone
Mobile phone units continue to drop in 2009 since beginning of 2008 due to the world economic melt down. A senior executive of Nokia told me that that estimated unit produced in 2009 will be around 87% of 2008, (decreases of 13%)
Nokia no long call their product hand phone but handset, as more and more function and feature are embedded on the so called Mobile Phone….GPS, Camera of 8-12 MP…MP3, Radio, TV, office tool, and soon PicoP Projector. The Hi End phone of $600-900 is on one side becoming more expensive and would prolong it life cycle more for 6-12 months. Since end user would need more time to get used to all the functions and it is expensive. Whereas more and more low end phone would be selling at lower cost of $80. ULC hand phone is gone!

White Box Hand Phone
Since 2006, a Taiwanese phone chip maker invented a single MTK chip. Since then it is much easier to make a phone design with the chip that usually took a few years to develop! A lot of White Box business was growing like Spring Asparagus! This has driven the Chinese LED market to supply more the Side View LEDs.

HBLED Growth
As a result of most powerful equipment supplier of LED bonder with Higher production Output per dollar investment over these years since 2003. As other electronics component cycles do, the ASP continuous to drop -12% while mass product makes its tribute to increase at +20% from 2004-2008.
HBLED Unit growth 25% to 48B pieces in 2008.

LED for NB BLU
(Note book back light units) has been commercially available in volume, from the very first prototype display NB unit Cree has made in its Hong Kong regional Office Open Ceremony with an astonishing $700 as cost for a 14” display in 2005. Now the cost is approximately 8% of that!

Net Book Impact
HP, Fujitsu, Acer, Dell, Samsung and Apple all have LED Back Light on its new models. Dell has announced that they will go for 100%.
And yet Net book had created a new market for LED, recently Samsung and LG had announced to go for the Net book market with unconcealed intention of pursue another No. 1 for that market.
The Total net book shipment is 13 million in 2008 and will likely have 26 million this year. End of 2008 and on ward will see a lot of need for Side View LEDs.

Automobile Market
Automobile shipment continues to diminish in 2009, the number vehicles world wide shipment drops 4.3% and for EU, USA and Canada market drops 10%. Though the use of LED is becoming more from 200 to 350 pieces on an automobile, the total LED on Automobile will not be an influenced factor for HBLED growth in 2009-2010. The AFL (auto mobile front Lamp) has been used just for three models of cars in 2008-9, (namely Lexus LS600h, Audi R8 and GM's luxury division, Cadillac has signed on with the German automotive supplier Hella KGaA Hueck & Co., to offer a solution - low glare Light Emitting Diode (LED) headlamps. will be offered on its Escalade Platinum edition SUV. GM has resolved as we do not know if this model will be continue or not or with other name? The only seen successful case is Lumileds who builds the Real Hi Beam LED head lamp for Audi. However due to limited demand at this moment, This AFL impact is insignificant to the LED market as their market demand is too small.

LED Signage and Display
There is growth modestly by LED back light unit LCD TV and monitors and LED projector. LED pico Projector produced but have little impact for the market in 2008. Let’s see how it performs in 2009!

Light Fixture using LED
More than 400 companies are entering this LED light luminaries.
A lot of new application is using LED, both interior an exterior lightings
Volume is small and price is high independent of various product qualities from different supplier. LED is penetrating of niche and general lighting application, growth was 39% but overall volume is still small.
The largest is Architectural market at 43% of market, White LED accounts for 50% of the market. Highest growth market is Outdoor, Replacement Bulb, commercial and industrial and entrainment.
Osram, Philips had introduced their LED light bulbs for direct incandescent lamp replacement. Theirs Price is $40-60 whereas there are numerous Low cost LED lamps using tens of VLED (vertical LED lamp) found in the market at $2-8!. This LED industry is still plagued by these low quality and underperforming LED light fixtures!

LCD TV
Is your home still using Big Glass Bottle of CRT TV? Probably not many!
Many New LCD TV sets from Samsung, LG, Sony, Sharp, are using LED as their back light unit, we have seen a lot of new model in CES 2009. Though there is just around 1% of the TV is using LED Back light LCD display, the upcoming market is Gigantic!
Samsung has launched an aggressive promotional Campaign of $40M. Would continue maintaining its NO, 1 position in LCD TV export world wide. And would differentiatel other with unique thin profile, super picture quality and they would enjoy substantial profitability. Price difference is still high between CCFL ($500 as an average at retail).
Sony is using Hi Power RBG Unit at edge lit configuration to have colour Gamut advantage over CCFL.

Samsung developed the direct back light using low power high enhanced LED for wide colour gamut, enable local dimming and High Contrast on 9 series as top of the line. And a leading adaptor or edge-lit as to trade of full local dimming with thinner profile of 29.5mm on 6000, 7000 and 8000 Series LED TV! In US the model is called Luxia. Edge-lit can have a thin 1” thick, CCFL is 2” thick, and 4” for Direct LED back light. Samsung Claims a reduction of 40% power than CCFL. LG LH 90 Direct back light unit, with a 0.94” thickness using Silicone lenses, Local dimming with 200,000:1 Contrast Ratio, less 73% power consumption using its Smart Sensor system. Sony Bravia XZ1 Series (edge-lit) 0.39” thick.

Other Factors
LED will obtain substantial momentum to grow on Lighting market.
LED will grow 15% in 2009. With the recovery of the world economy, this will have >20% growth in 2010. Direct colour and intensity control plus colour mixing function functionality enhance the broad acceptable by many application designers. Continuous improvement in LED efficacy will further secure the adoption of LED on general white Light market. Maintenance free, long life time plus government body subsidies and regulation (EISA 2007, Title 24 California, EU regulations) are important market Development trigger.

Technical Challenge
Yet a lot of challenge ahead, Human Naked eye is sensitive to see slight different white color changes induce heavy burden for LED Company to product consistent colour, sorting cost becoming higher and handling of logistics in the sorting and binning process an bottle neck for as many as 512 bin Grades. Designing high efficient fixture with simplicity such as AC LED would be a way to reduce the overall installation cost of lighting application. Realistic claims of LED life time, LED fixture efficiency, Life time, quality of light Fixture, heat dissipation rate should be improved to win Customer’s confidence before mass materialization. I have seen a lot of Traffic Lamp, Toll display LED, and Even Hong Kong Express LED light fixture has lot of black out LEDs….
It requires some time to show that the real LED should last. Although I can not deny that some of the LED failure is not just the LED or the associated driver unit!

LED quality
However, as an overall quality, every piece of component should involve good quality engineering design and process optimization and stringent good quality control in the manufacturing stage. Least but not last, the use of proper Good Quality Bonding equipment; die Bonder AD830 and Wire bonder iHawk which are well accepted by almost 80% of the major users in the world.

Overview of 2009 market
The overall market atmosphere is still low until September 2009 that it finds its bottom and will start to grow. We foresee that it will embark a friendlier environment for LED to grow at a higher rate. The major growth is LCD BLU and SSL (solid state lighting) market segment in 2009

Forecast 2010
According to Strategies Unlimited the HBLED market grow will be resumed in 2010 and a CAGR of 19.3% till 2013 with revenue of $12.4B.

Data source: Strategies Unlimited reports

More Display sign boards go LED

Modern Gas Display is now going LED and are completely wireless control for the display input.

Installation within couple of hours will have advantage of great Visibility, Wireless control for 46M, Maintainance Free, Operation for 50,000 hours, Simple Operation...

The NurseCall, Door display, welcome boards, plus numerous application for LED signage display with more and more of them are equipped with remote control.

Advantage of using LED

You are saving considerable power and money by using LED lighting fixtures.
The efficiency of LED lighting fixtures is almost 8 times higher than those using incandescent lighting and 2 times higher than compact florescent ones.

The LED-based fixtures give out a higher light percentage towards the desired direction due to the high-technology optics they are fitted with. This makes them even more efficient than classic lighting solutions used for both architectural illumination, interior lighting, decorative or ambient lighting.

Unlike incandescent light sources, LEDs generate low heat. The EPA (Environment Protection Agency) constantly encourages us to use innovative solutions for light sources, like LEDs. In normal operation conditions, the lifetime of LEDs is approx. 100,000 hours; considering 24/7 continuous operation, LEDs could very well work for more than 10 years.

LEDs are not sensitive to mechanical shocks, vibrations or sudden temperature variations, which are known to be destructive for incandescent or fluorescent lamps.

Unlike classic lamps, LEDs are not affected by repeated on/off cycles. When turned on, LED-based lighting fixtures provide fast and maximum intensity light. Typical response time for LED to be switched on is 20ms, take for an example, the AFL (Automobile front lamp) for a car running at a speed of 100KM/hour, the sudden turn on of the head lamp can light up 13.5M more distance ahead your Car to avoid an accident than the HID, which may take 0. 5 seconds to be fully turn for intensity.

Even in low temperature conditions. LED-generated heat is much lower than that generated by incandescent lamps, which might even cause fires in numerous occasions.

LED can have different colour, with certain control it can have numerous changes on colour for display purpose.

LED can be used a BLU to LCD display, edge lit or full panel back lit. It can provide local diming for achieving up to 2,000,000:1 Contrast.

LED can be used to detect the Oxygen, carbon monoxide level inside blood instantly by clipping the sensor on your thumb, while the sensor is connected to a handheld analyzer and display.

The applications of LED has not come to an end! With your imagination, we are sure there are many more to come!

No One Can escape from the Miserable First Quarter?

According to iSupply Corp., no one is immune in the miserable condition of first quarters 2009 as a continuous dwon fall momentum of market need Q4 2008.
Worldwide Semiconductor Revenue in Q109 declined to $44.2B, 18.8% as comparing with $54.4B in Q408, and a decline of 33.8% from 66.8B in the Q108.

On positive side, Revenue will rise by 7.1%, 10.4% and 4.95 in Q2, Q3 and Q4 respectively.
Amongst the players. We see Osram, one of major suppliers for LED, is in the list; as probably due to change in exchange rate would be an notable impact on the revenue growth when converted to common dollar basis.

Robert Yeh, chairman of Everlight Electronics Inc, Taipei, June 15, 2009 (CENS), said at the Photronics Festival in Taiwan 2009, held June 10-12, that supply of LED chips is expected to fall behind demand until the second half of 2010, with prices to trend upward.

Yeh is optimistic about industrial prosperity in the second half of this year through next year, stressing that demand from notebook PC, TV and lighting sectors has infused strong growth momentum into the LED industry. Particularly, he added, increasing popularity of LED-backlit LCD TVs will serve as major growth drive this year.

I am confident that LED market will keep growing in the next three Quarters! More competitive device will be made in the market in larger scale, the Equipment supplier will have go into this hot market will fast pace or will be erased by their competitors.

Who will win in the LED TV competition?

There is a realistic launch of LED BLU LCD TV in the market beginning of 2009 after numerous attempts for customer test out at Shows from Players such as Sony, NEC, Sharp and Samsung in the past few years!

Though there are different ideas on this market. Even optimistic market researchers would say that will be need a time to see how the market reacts as the price of the LED TV is higher than CCFL or HCFL LCD TV, the Japanese TV makers are keep an eye in their launching out for more portion of LED TV while Samsung and LG is pushing at full scale promotion on this.

I saw full series of LED TV displayed at a renowned electronics store at Ocean Centre, Tsim Sha Tsui with a huge Sharp Aquous LED TV 56” with RGB BLU, the colour was glorious and picture quality is impeccable! That may be a show case for them to participate in this TV Sales competition as the Selling price is over HKD140,000.00. I was in profound shock to see a Sony LED TV with absolutely vivid picture stood up in the TV beauty pageant. Same thing happens in Penang, Hong Kong and Singapore, Samsung is seen having the most aggresssive promotion for the LED TV Series 6, 7 and 8. Series 6 is basic type, 7 wth more feature and 8 with 200HZ Motion plus. Series 9 is Samsung's flagship 2nd Generation HD LED TV with SmartLighting Local Dimming Technology.

From this point, I think of the book "Samsung Vs. Sony” written by Sea-Jin Chang.

Chang made a lot of example and cases studies on these two Electronics Giants;

Prince and Pauper in the Analogue world

There are only two ways for Sony to avoid imitated by others; one is to set product standards on our own and the other is to have mechatronics, embodying our craftsmanship.
-Noria Ohga, former CEO of Sony


Compared to other semiconductor products, the design technology of DRAMs is not so complicated, but the market for DRAMs is fairly large. We decided to focus all our resources in one product where we could do well. We had to take a lot of risks. In addition, fortune was on our side. The timing was great.
-President Yoon-Woo Lee,
Semiconductor Division of Samsung Electronics

In 1987, Samsung’s investment in DRAMs started to pay off. That year, the U.S. government raised an anti-dumping suit against Japanese semiconductor manufacturers. In the wake of this accusation, the U.S. Government and Japanese manufacturers reached a voluntary export restraint agreement to the United States.

Soon afterward, the price of DRAMs began to rise. Demand for the 256K DRAM grew especially rapidly, but Japanese producers had already reduced or closed the 256K production line or shifted much of their capacity to the 1M DRAMs, believing that the 256K production lines were outdated.

In contrast, Samsung’s main DRAM product remained strong on the 256K Chip.

Samsung’s profit surged, in 1988, Samsung’s profit were large enough to offset all its cumulative losses.

In fact, Samsung’s investment in manufacturing facilities in 1987 contributed to its success in the semiconductor boom, which continues into the early 1990s.


This success was possible because Samsung management believed that only by investing during recessions could be the company reaps great profit during the boom period!


The technological and product profolios of Samsung Electronics are very different from Sony’s. Samsung Electronics invests in technologies that have clear trajectories with clear evolutionary progress and industrial standards.

Even the late-comers can succeed in such businesses. Also, Samsung has taken Moors’ law to heart, the principle states that degrees of integration doubles every eighteen months, by doubling its efforts in R &D to develop new products according to this schedule. This effort provided a very simple and unified goal for all Samsung employees.

For example, because the 256M DRAMs would be the next-generation DRAMs within 18 months after 128M DRAMs, the only mandate would be to develop 256M DRAMs within 18 months, having all its employees committed on this single goal.

Similar trends exits in many of Samsung Electronics’ other businesses, For instance, there is a trend called “Hwang’s Law” in the flash memory sector, named after President Chang-Kyu Hwang of Samsungs’ Semiconductor Division. This states that the degree of integration doubles annually.

In other areas, such as Samsung mobile phones, Samsung has become leader at rapidly adding new features (such as cameras and MPS player), miniaturizing technology, and reducing costs, As a result, the life cycle of mobile phones has become shorter and shorter. Just like DRAMs.

Similarly, LCDs have a clear technological development, increasing the panel size while improving its yields.

In short, Samsung has invested in businesses for which it could have the highest return given its resources level, and unlike Sony, it has not hesitated to source technology from other firms and other countries, it has been only in the last 15 years that Samsung Electronics has begun to develop technologies in-house.


Speed is the key to all perishable commodities from sashimi to mobile phones, Even expensive fish becomes cheap in a day or two. For both sashimi shop and digital industry, inventory is detrimental and speed is everything.
- Jong-Yong Yun, CEO of Samsung Electronics

Samsung’s Success story:
A result of focus investment on future product meets the foreseen trend of product cycle!

Sony’s failure story:
Too narrow on vision on the company direction and too slow to react to the market with most of the industry standard and users are expecting. Swimming alone against the tide is tired for Sony!

There is hot topics in the Chinese Bloggers LED “三国演义”as China, Korea and Japan are the Three Countries competing for this market. Give us a couple of years we will see who will be the ultimate winner, and to most of the LED suppliers. They are all the winners!

Watch out that the LED TV is account fo kust 1% of the total LCD TV production in the World., there is a big market for the LED to go into these area… let’s be optimistic on this challenging technology to go into the consumer markets.

No one could not disagree that a 42” TV with RGB TV with a built in PC for colour and dimming control would be selling USD1,000.00 in three year times?


Reference.
iSupply Corp.
Gartner
The Book “Samsung Vs. Sony” by Sea-Jin Chang (ISBN 978-0-470-82371-2)

Microvision Pico Projector

Microvision

Microvision is working with business partners to enable better viewing experiences for mobile device consumers. Sharing photos, watching movies, and giving presentations using the small screens of today’s devices limits our ability to imagine, entertain, and share.

PicoP

Pico P is an ultra miniature projection module capable of producing full color, high-resolution images but small enough and low power enough to be embedded directly into an accessory pico projector that connects to mobile devices.

For manufacturers who wish to bring to market next generation accessory projectors that connect to mobile devices, Microvision provides a PicoP display engine to meet OEM requirements. PicoP display engines are engineered for OEMs and made available through our supply chain partners to meet high volume production needs.

Specification for the Projector
10 lumen 848x480 pixel
16:9 aspect ratio, 60 Hz Refresh rate, 5000:1 Contrast
69 grams 68x68x10mm
Image size 6”to100” depending on ambient light and condition

How it works?
http://www.microvision.com/pico_projector_displays/howitworks.html

Some LED Players

Shuji Nakamura

Lumileds K2 Power LED

Cree XLamp 7090

Avago Technologies

Avago Technologies is an American company which was earlier the semiconductor products division of HP and later Agilent Technologies, before being spun off into a distinct legal entity. It holds more than 2,000 patents.

In late 2005 the semiconductor division of Agilent was acquired by Kohlberg Kravis Roberts and Silver Lake Partners, and became an independent company. Today it is one of the largest privately held semiconductor companies in the world, with approximately 6,000 employees and net revenue of $1.8 billion in fiscal 2005.

Avago Technologies provides a range of analog, mixed-signal and optoelectronic components and subsystems to more than 40,000 customers. Thin Film Bulk Acoustic Resonator (FBAR) filters are produced for mobile phones and WLAN.

Avago is also one of the world largest LED manufacturers. They produce billions of LED a year for different application. Product portfolio covers through holes LED, Surface mount PLCC, Envisium Surface Mount PLCC-4 LED, Moonstone High Power LED, Moonstone High Power RGB LED and various kinds of indicators and displays.
"Avago" is an Australian slang word. It means, "Give it a try - have a go."

Cree Inc.
CREE is a Durham, North Carolina based, American corporation which manufactures semiconductor materials and devices. It was formed in 1987 by researchers from North Carolina State University. Materials products include silicon, Silicon Carbide (SiC) and Gallium Nitride. Device products light-emitting diodes (LEDs) made from their materials for a variety of uses, as well as power supply chips, motor controllers and microwave radios.

The wide band gap semiconductors are suitable for high voltage or high power or high temperature operation. SiC is used for high power electronics, largely due to having a very high thermal conductivity.

Two directors of Cree are John Palmour and Chuck Swoboda.

Cree's high-power LEDs, XLamp 7090 XR-E Q4
Some operations are now located Tai Po Science Park in Hong Kong. The company's silicon fabrication line in Sunnyvale, California is closed, and the company is now focusing on wide band-gap technologies.

The company produced a prototype White LED that can produce 161 lumens per watt while drawing 350mA of current, nearly 10 times what an incandescent (normal) light bulb can produce. As of March 2009, the most efficient white Cree LEDs commercially available, such as the XLamp XR-E R2, achieve 100 lumens per watt. Based on more than 20,000h of continuous testing, Cree estimates that XR-E LEDs will lose 30% of their brightness over a usage period of 50,000h (barring overheating).

Cree bought Cotco Hui Zhou in 2007 with USD$300 Millions , that is another step moving from Chip manufacturing into a highly vertical Integration of Package LED manufacturing.

Cree's competitors include Nichia Corporation, Osram Opto Semiconductors, PhilipsLumiles Lighting Company and GE Lighting (Vio). Cree is also facing increasing competition from low cost Taiwanese LED manufacturers such as Epistar and Everlight.

Everlight Taiwan
Everlight Electronics was established in 1983 and has played a critical role in Taiwan’s LED industry. In 2006 Everlight established itself as number one in terms of market share in Taiwan with second place significantly behind. Liteon In 2007. Everlight Electronics continued to lead the Taiwan market in both total revenue and in revenue growth rate Now. It established itself as the seventh largest LED manufacture in the world.

Everlight Electronics maintains assembly lines in all product series including High Power LEDs, LAMPs, SMD LEDs, Display and Infrared products. In addition to having the complete product series and a large manufacturing capacity, Everlight also integrated vertically by investing in LED optical chip manufacturing in order to maintain a stable supply of chips. Everlight Has factories in Taiwan and China.

Overall, Everlight’s competitive advantage is its manufacturing. The new awarded Product is Dolphin HB LED. Noteworthy is that Everlight unveiled its newest AC LED at the show, which can work without transformers and last for 50,000 hours, and was, scheduled to start shipping the product in the fourth quarter of this year.

Everlight today is a $300 million company headquartered in Taipei, Taiwan, with over 4,000 employees and operations in China, Asia, North America and Europe.

I still recalled that I was the one to install the first two Die bonders in Tucheng Taipei when Everlight was still not as big s today in 1988. How this is the Taiwan Largest LED manufacturing.

LedEngin, Inc.

LedEngin, Inc. is a California-based solid-state lighting company specializing in ultra-bright LEDs capable of emitting 2,000+ lumens, delivering extreme flux density and industry leading reliability as well as luminous efficiency >80 lumens/Watt in some applications. The Lux family of replacement lamps and lighting modules provide superior quality light in directional applications equivalent to 35W and 50W halogen lamps. LedEngin also develops LED custom solutions and provides expert application support on optical, electrical and thermal management. For more information, email LedEngin at info@ledengin.com or visit http://www.ledengin.com/.


Liteon Taiwan
Lite-On started producing LED products in 1975 and has steadily grown into one of the world's largest optoelectronic component manufacturers by providing customers with both visible and infrared product solutions. High volume capacities for commodity items and application specific products, combined with strong R&D and vertical integration, have proven to be key distinguishing factors in Lite-On's success. Our broad product line continues to expand to meet the requirements of emerging markets and new applications. Liteon had factories in Thailand and Tianjin of China.

Lumileds USA
In the late 1990's, recognizing the potential for solid-state lighting, HP and Philips, one of the world's leading lighting companies, began exploring how they could work together and deliver a new solid-state lighting solution to the market. In 1999 HP split its company into two, and the optoelectronics group was assigned to the new Agilent Technologies. In November of the same year, recognizing the enormous potential for LEDs, Agilent Technologies and Philips (NYSE:PHG) formed Lumileds and assigned it the responsibility of developing and marketing the world's brightest LEDs and enabling a new world of light.

In 2005, Philips acquired Agilent Technologies’ interest in Lumileds. Today, the company continues to lead the industry in the development an Philips Lumileds Lighting Company is a fully integrated manufacturer of LED dice, packaged LEDs, and high-brightness LEDs

LUXEON®—designed for integration into general lighting products. The company markets LED solutions designed specifically for automotive applications, LCD displays, general lighting, portable applications, signage, traffic signals, and other segments. Philips Lumileds makes the world's brightest white, red, amber, blue and green LED release of increasingly brighter and technically advanced solid-state lighting technology.

Philips Lumileds' LUXEON® technology enables LEDs to match the brightness of conventional light sources and for the first time, makes it possible to replace incandescent, halogen and fluorescent bulbs in many products with smaller, longer-lasting and more energy efficient LEDs.
Luxeon is the trade name for high power LEDs that dissipate 1 watt or more. Models include Luxeon I, Luxeon III, Luxeon V, Luxeon K2, Luxeon Star, and Luxeon Rebel.

Luxeon LEDs produce powerful light, and are a popular choice among flashlight manufacturers. They are available in many colors, including white. Luxeon is in fact the first kind of an innovation design and had absolutely good thermal design LED.

Probably the only one using TFFC (Thin film Flip Chip) technology for LED manufacturing.
Competitors to Luxeon include Cree Inc., Seoul Semiconductor and Nichia Corporation.

Nichia Japan
The Nichia Corporation (日亜化学工業株式会社, Nichia Kagaku Kōgyō Kabushiki-gaisha) is a Japanese chemical manufacturing company that is most widely known for producing phosphors, including light-emitting diodes (LEDs).

The Nichia Corporation was founded by Nobuo Ogawa (小川 信雄, 1912-2002) in 1956. One of his famous decisions was to support Shuji Nakamura (1954- ) to do research on Gallium Nitride light-emitting diodes when it was generally considered a very risky business. It turned out to be a great success. However, the company achieved a certain amount of notoriety for awarding a bonus of ¥20,000 Yen (US$180) to Shuji Nakamura for his invention of the first high brightness blue-light LED, which was based on Gallium Nitride. Nichia later settled out of court with Nakamura for ¥840 million Yen (US$7 million), in what was then the highest bonus ever awarded by a Japanese company.

After Nobuo Ogawa, the company was headed by Eiji Ogawa (小川英治, son-in-law of Nobuo Ogawa). Nichia Corporation's competitors include Seoul Semiconductor, Cree Inc, and Philips Lumileds Lighting Company.

Osram Germany
The name is derived from Osmium and Wolfram (German for Tungsten), as both these elements were commonly used for lighting filaments at the time the company was founded. OSRAM is a high-tech company in the lighting industry. Around 60 percent of sales come from energy-efficient products. Its was established in 1906, many years before that they have started the manufacturing of Incandescent Light bulb!

Litronix, original backbone and engineering team in Pennag 80’, and Siemens worked with Litronix and used Siemens Litronix since 1989 and then brought all manufacturing equipment from Siemens Malacca to the current Location in Penang with Factory “ Siemens” Then later Changed its name to Osram. Osram has been building LED in Pennag for more than 20 years. Today it is Owned subsidiary of Osram, Lighting manufacturer, a Industrial sector of Siemens. Osram, headquarters in Regensburg, probably the oldest Lighting company in the world. Since 1842.

With its headquarters in Regensburg (Germany), OSRAM Opto Semiconductors is in an excellent position to meet the challenges faced by a global high-tech company. More than 4600 employees throughout the world contribute to the success of OSRAM Opto Semiconductors, producing sales of 529 million Euros in the 2008 fiscal year (as at 30.09.2008). Around 12 percent of the sales of OSRAM GmbH are achieved with semiconductor products.

Major Product is Gold Dragon, Power TopLED for general illumination and Ostar for Hi Power illumination application.

Colour Rendering Index CRI

CIE 1960 UCS. Planckian locus

Colouring Rendering

An object looks whitish under the fluorescent lamp and meanwhile, the same object looks yellowish under the incandescent lamp. The Same object looks different in (or under?) different light sources. You can see light source change the colour of objects by comparing under fluorescent lamp. Incandescent lamp, daylight and etc.
Colour Rendering is the property of the light sources that affects the colour of the object.

Colour Rendering Index (CRI)
CRI is a numerical representation to evaluate the Color Rendering Properties of the light source.
CRI Shows how accurately a sample light source reproduces on object colour compare to The *reference Light Source.

The CRI value of 100 means the sample light sources reproduces the same colour a the reference Light Source does. Therefore the higher the value of CRI, the more it resembles to the reference light sources.

When evaluating CRI, the reference Light Source is chosen to have the same (or within the range of 5 mireds) correlated colour temperature as the same light source.

* Reference Light Source
a) Lower than 5,000 Kelvin: Planckian Radiator
b) 5,000 Kelvin and higher : CIE Daylight

LED Graffiti Throwies

Developed by the Graffiti Research Lab a division of the Eyebeam R&D OpenLab, LED Throwies are an inexpensive no-clean Graffitti to add color to any ferromagnetic surface in your neighborhood.

A Throwie consists of a lithium battery, a 10mm diffused LED and a rare-earth magnet taped together. Throw it up high and in quantity to impress your friends and city officials.


Everything began with a campaign in Manhattan in which LED throwies were handed out and people were encouraged to throw them onto a large metal sculpture called Alamo.


The spread like wildfire on Internet, and just a few weeks later they were spotted in London, Hamburg and Berlin. But not yet in Hong Kong!

How to Choose my TV?

CO2 Emission
HONG KONG, 28 March, 2009 – At 8.30 pm. the city of lights went dark and joined 4,000 other cities and towns in 88 countries in an hour of global solidarity. There were more than 1,800 buildings, 600 companies and 160 schools joined this program to off the light, an equivalent to 5% of electricity that is an equivalent of 170 Tons of CO2 emission. In order to absorb this 170 Tons of CO2, we need 380 trees to breathe for 40 years!

Product Design
As CSR company, we have to design product with minimum operation power, environmental friendly material and non toxic recycled packing material. Scientist and electronics circuitry designer are studying in vigor to reduce the power consumption. Less Power consumption pushed the design towards a stringent components selection, tighter Incoming parts tolerance, use of smart logic to reduce unnecessary operation of component in certain application, thus in turn reduce the use of heavy heat sink, cooling fans and redundant electronics modules. Imagine that almost no TV is using massive power transformer anymore. They use Switching mode power supply for smaller footprint and is much lighter, of course cheaper.

Electricity Bill
Domestic illuminations accounts 22%, Air Con for 34%, fridge for 14%, and TV take as much as 7.3% of total monthly electricity bill amount. As For TV which consumes as much 8% of electricity, we could not underestimate the Green TV would have create much less CO2 emission every night you are watching your huge screen TV!

From iSupply’s recent survey, customers are looking for two factors in buying TV: price, and how Environmental friendly the TV is!

Sharp ran a similar questionnaire on 1,002 Americans in Mar 2009, found out that 72% of them would prefer a good price, Green and Power saver design TV.

Standard for Power saver Product
In Hong Kong, there is Energy Label issued by EMSD by 5 grades with “1” as the best performer, “5” the least. There are EnergyStar saving standard in US, In USA, Energy Label in Europe, and EECJ Energy Saving label in Japan.

TV Review
Now UK TV review will cover these major categories. Take for an example for Sony KDL32S5500 LCD TV
Eco-cost of £22.13 per year, based on being switched on 5 hours a day at average Electricity rates.
Its carbon footprint therefore is around 96.92 kg CO2 per year.

Sony TV
Sony had been leader in Product innovation, technology achievement and trend Creation in the 70-80’s. Still recall that Walkman was the craze in the 80’s a successful creation from Sony, the word “Walkman” entered in the Webster Dictionary. ”Betamax”, another technology yardstick of technological achievement, not a commercial success for Sony on Video Recording, due to an uncompromised dispute between Sony, JVC and Panasonics for video system standardization.

Bravia designed with usage of HCFL backlight help reduce in-use power consumption by Approx 40%. Comparing with Sony three types of TV with different structure of Backlight design namely

Sony CCFL, HCFL and LED back light TV

A). Sony KDL-46W4500 CCFL Backlight with average power consumption 230W ( HKD$23,880.00).

B). Sony KDL-46WE5 HCFL (4mm dia.) backlight which consumes a 40% than CCFL (HKD$24,880.00).

C). Sony KDL-46X4500 using more than 1,000 RGB LED as back light, Available 46 and 52” size available (HKD$39,88.00)

Electric Bill
Tests have been doen for these three types of TV the result is :
A). CCFL has average power consumption 230W
B). HCFL has an average power consumption of 150W
C). LED has an average of 200W

Assuming we turn on 8 hours a day and assume HKD$0.90 for 1KVA/HR

A). Sony CCFL TV is HKD$600.00 a year
B). Sony HCFL TV is HKD$390.00 a year
C). Sony LED TV is HKD$525.00 a year

So LED is not the least power consumption backlight system yet. But the performance in contrast is stunning especially the Darkness interpretation is outstanding as they have local dimming function by running off individual LED spot that is HCFL is no way to achieve.

We used to buy TV from brand name in the 60’ as we have popular brands like Bush, Siemens, General Electric, Philco, Blaupunkt, Saba, Telefunken In the 70’ we started to have Sony Trinitron, Denon, National, NEC, Toshiba… in the 80’-90’ we have those B&O, Philips, Sony, Panasonic (National) in 90’s. Now it is the era of the emerging Korea Giant Samsung, LG take 22% and 13% market share of 2009 Q1 World LCD TV shipment.

We can summarize in tree phases, European as the leader in the 60s, at that time Japanese was leaning how to build radio and after 10 years, they could manage to produce quality TV for humid Asian market with success. Amazingly, Now Samsung could produce best quality and with all kind latest technology embedded onto a TV with LED back light at a thickness of 29 mm!

TV Selection
Compare picture quality by using the same input source
Check power consumption, Check the heat generation at the back top side of the chassis. Cooler is better. Warranty period, some of them has 3 years warranty

Go buy CCFL backlight if you are under budget, through they have mercury in the manufacturing process if CCFL, the price is lowest, but the electric bill is highest.

Middle of the road
If you are looking for certain level of good quality between CCFL and LED, HCFL is the choices. And price is affordable.

Celebrities, movie freak and technology lovers
If you are looking for best picture quality, new technology, and a Green TV LED backlight is not a question the best amongst all but you have to pay for a premium. Forget the CCFL or HCFL, they are not built for you!

Plasma TV
How about Plasma TV? They were made with short life time 10 years ago, but this is already history as they can product a very reliable Plasma Display now. Its power consumption is also outstanding, but the consumer is leading the market a Plasma TV is only aprox. 1% of all the TV. Lesser people will go for Plasma TV.

As for my personal comment Plasma TV is some thing like Leica M6 and LED TV is something like your Leica M8! If you do not have Leica camera, try to compare this way: Plasma is like LD and LCD is DVD… so there you can see the difference? If for say very large panel display, Plasma is still having the brightest and contrast you can see. And at a lower cost. No a bad deal!

My Choice
Samsung UE46B7020
Samsung always ensure all the best features are on board with their TV's and the UE46B7020 has not been overlooked by a long shot. By using mercury free LED lights less energy is required and less carbon dioxide is emitted making it a very environmentally friendly TV. Picture quality is kept to a very high standard and Samsung claim that the three C's are required for this: contrast, colour and clarity. This has been achieved with a Mega Contrast Ratio, a Wide Colour Enhancer pro and 100Hz Motion Plus Technology. The ultra slim depth has been achieved by a single, solid, seamless body rather than separate parts being moulded together creating an amazingly thin and sleek model.

feverip

Soft Solder Process for HB LED manufacturing

There is numerous ways to mount a die onto the substrates either made of Copper, ceramic, Leadframe, PCB, and Alumina, or a Pre-mould PLCC leadframe material has to go through a series of consideration. Refer to the attached tables. It is self-explanatory!
We can see that we have to first decide what kind of package we want to build, and for what application. Say if that is made for out door illumination, or For AFL (automobile Front lamp) that will be very harsh for the LED package as we require to pass a stringent Stress cycle requirement. The way how we can cool down the chip is the prime consideration.

Of course, the temperature can be made by force air cooling in an automobile, but in the case of a car running in dessert high way, the LED will be very hot. The junction temperature may go up to 125 Deg C. if the heat sink is not ale to carry out the heat, their performance of the chip will deteriorate and or soon burn out.

Seoul Semi new SMD LED package
12th May, there is a novel design of LED from Seoul Semiconductor to launch of its 120lm/W
high-efficiency and SMD type LED (Part No: LCW100Z1) for general purpose lighting.

As an ultra-thin LED with dimensions of 3.5mm x 2.8mm x 1.6mm, the LCW100Z1 is a high efficiency product that delivers up to 7.8lm (@0.06W) at the low current of 20mA and 14.3lm at the current of 40mA, and its viewing angle is 120 degrees.
This is a silver epoxy on Copper substrates. The heat dissipation should be more superior than the other type on ceramic and PCB. However, they can not achieve a very high BLT more than 1.5 mil, so there is still room for certain performance improvement.

Die Bonding Process
Direct Eutectic process is expensive for the 80/20 AuSn layer which has to be thicker than the surface roughness of base material.

Flux Eutectic process has it drawback as the flux will be the trouble they give up in the years to come for Lens Contamination and Delimination.

High Silver Content Epoxy Bonding
Having limitation in void control and not perfect for CTE matching as it is not easy to product a high enough BLT without any epoxy tailing issues with zero void.

Soft Solder Process
On the other hand Soft solder has been widely used for automobile and power device for more than 40 years. Soft solder has excellent heat-dissipation properties, of typically 35W/mK. high ductility, exhibited outstanding robustness against declamation. During thermal stress condition the solder can withstand a great thermal stress caused by asymmetrical thermal expansion of LED material SIC and Copper (SiC CTE is 3.1~4.7W/k-m and copper is 16.5ppm/K). These extraordinary characterizers lead us to consider an ultimate process for LED.

The remain four challenges are to maintain an Solder coverage, zero void, good die bonding placement and die tilting.

There is some challenge on the solder coverage as the LED chip is thin as 6 mil for EZ1000, and that will be some challenge to have both 100% Void free and good wetting for four edges. However that is research that one company has the solution, and they have actually can achieve +/-20 micron die placement with practical Zero void!

Soft Solder LED process
Basically this is a novel bonding process that requires precision, good temperature profile set-up and hest tunnel design with consideration of the formic gas flow, with CAE and proper het insulation material a standard solder dispensing system with accurate amount of solder to be place on the substrates. A high speed bonding head which can sustain a high temperature with minimum controllable thermal expansion or active alignment on every start of bonds using patent optical alignment method. Also there is a Reflow concern, if after two to three time reflow the solder will be softened and cause the die to be lift up, That will kill the process, If using solder haveing lead, that might not be good for the Product. So this is a kind of delimma, yet to be solved!

Solder Void
Since the die tilting and void will create uneven distribution of solder underneath the die, this void will reduce thermal and electrical conductivity and hence heat dissipation will be reduced These will create a higher electronics resistance. Moreover, larger void are often the beginning of an elimination of the die from the solder, which mean life time reduction. The Void has to be close to zero of more than 2% of the total area under the die.

BLT and Die tilting issue
A consistent BLT requires the Centre of the solder dispense dot to be properly aligned with each other. That is to have the vision of other mechanical way to properly align their two centres to be on point. As the Solder will be flowed back a few milliseconds after the collet has placed the die onto the solder, the solder will be squeezed out and once after the collet is move up, the capillary effect would work from four sides of the die bottom to pull in the solder. The smaller the die , the smaller the capillary force and more critical to properly align the die by the molten solder as there will be having insufficient or no flow back of solder material.

If the die is not placed at the centre of the solder lump, one the edge having minimum solder will not be having the same amount if pulling force as their other three edges and hence a tilted die will occur.

Vacuum Delay and timing
The proper control of the vacuum release is critical for controlling the BLT and Tilting of the Die.
The wrong timing for vacuum release will create die tilting issues, either too early or too late of the timing , especially for smaller dies. If the delay is too early the die will lose control as die falls onto the solder without control. I the vacuum release is too late, the collect will suck back the die.

Mechanical alignment
There is perfect coplanarity for the Collet to be level with the bonding pad, as well between the solder wire dispensing head with the bonding pad.

Purge Air
On the other hand there is used to have certain Purge air at the collet such as to break the vacuum aster. That amount of purge air can cause die tilting as well, in any sense, can not set too much, and that purge air should be so adjusted by software to be controller in proportional to the die size.

Conclusion
Soft solder process has been running in the power device for more than 40 years. That is a mature process. However High Power LED using lead free Solder is a novel process, there is a lot of challenge such as reflow issue for major reliability concern. How to control the amount of Solder is the key point. The advantage is cost and zero Void, and highly reliable LED product could be made! Another step jumping into the Replacement light bulb application.

Who can manage to use the low cost process for best final product reliability will be the one who can win the market.

When will LEDs be truly able to replace Screw in Light bulb?

This was one of the hottest topics some 14 years ago when we met some of senior marketing staff of one European incandescent lamp company saying that the LED screw in light bulbs would be come a commercial product 10 years later, waited until 2004, well, still could not see that to be materialized!

There was great promise and a prominent wish, but the path won’t be easy. Key persons of the major LED players such as Osram, Lumileds and Cree had numerous discussions about this over the years in many consortium and LED shows.

The answer turned out to be less than simple. For one thing, a typical 5mm LED produces about 6 lumens. A commercial lighting fixture would require hundred thousands of such LEDs, bring more technical concerns for driver designers, and in the end consuming more or less the same power as a florescent lighting fixture of the same output.

The pros of for LEDs in lighting fixture comes when you design the LEDs for that purpose, and LED can achieve higher output efficiency, directability of the beam, and reliability that you can’t get any from the best CCFL.

Recently there are a lot of replacement LED light bulb made in large quantity using standard 5mm LED, and sooner we see more and more failed and or burnt out. That was because they are overdriven to the limit that it can designed to withstand, over driven a LED will degrade the epoxy encapsulant. Then the epoxy becoming yellowish, and gradually it starts to crack, once it cracks, the LED will likely to fail.

On the way I returned from Malaysia a couple of days ago, I went to inspect most of the LED lamps that was made with 20 over vertical Lamp in the Airport Express Train at HK Airport.

Obviously that I could see at a low of failed LED in each light fixture. And No one is found to be full lighting up. The train has been running for over ten years and that is the life time for the LED, well I could see that they may not using the bets of his kind and I could remember that the light intensity drops as time goes by!

The lure of the huge compact incandescent-bulb replacement market would seduce the supplying food chain for low cost replacement light bulb using LED by Asian Suppliers, coupled with the entry of low-cost white box producers from China, quickly drove vendors to trade away the long life in exchange for lower cost.

This led to an unfavourable situation in which general consumers often don’t understand the quality of the LED lamp they are buying. In fact in many applications, inexpensive LED light fixture aren’t really direct replacements for ordinary light bulbs or CFL lamp at all.

The consumers buy the wrong bulb for their purpose and get frustrated when it doesn’t work. In China, now we can buy from the market of some bundle of 20 5mm LED light bulb at a price if merely RMB18.00. (USD2.0) This is a incredible low price for the number of LED they have, the chip and associated circuitry. But who know how long these LED can last. Do not forget a typical good quality LED can last 50,000 to 60,000 hours.

All LED designer is doing the best to use different material, manufacturing process to build a LED with good conductive cooling. The incandescent lamps are designed to survive with only radiation cooling. And today, the cost per Lumen of LEDs is still 10X-20X more expensive to replace CFLs and incandescent lamps respectively.

This price different was 20-40X two years ago, the ASP of these good LED is dropping at a mush faster rate that 5 years ago. In order that the LED bulb to be made successful, it has to be reliable, the fixtures must exploit the long life of properly-designed LED lighting to have a competitive position.

On the other hand , the EnergyStar standards will be critical to the development of this market. The beauty of LED lighting is not its cost, or even its efficiency, but the features that it can offer beyond just illumination. Today a typical screw-in light bulb is not expected as cheap as the energy lamp nor the incandescent lamp.

Most of us is using low-cost manufacturing in Asia today. The difference in cost of LED lighting is in the choice of materials and or type of the die bonding process. For instance, you can choose to use inexpensive epoxy that will fail, or you can choose to replace it with a thin film flip chip process which does not contain any epoxy and with excellent gold to gold heat dissipation to keep the LED cool, and there is resistant to light degradation but are more expensive as at price of few times higher.

The substrate, the type of bonding process either epoxy, direct Eutectic, flux eutectic or flip chip, the phosphor that goes over the LED and adds a yellow component to the LED’s blue emission to product white light *1 and the die itself are the key components in a lamp. There are lots of trade secrets and IP in this business, and most of the LED manufacturing or suppliers are quite vertically integrated.

There’s only a core set of companies that have the IP for white LEDs. That could limit competition from low-cost producers copy cats who don’t know how to do it well.
Many consumers have had access to long-life light bulbs, and have steadfastly unwilling to pay a premium for them. Of course there are certain pioneers who has been using LED light bulb at home, hotel as street lamps.

Nowadays there are 70 percent of the lighting-fixture market in the US is commercial, only less then 2% of the user are residential. Incandescent lamp sales are declining as people switch to more energy-efficient lamps such as energy saving lamp as the majority. US and other advance country in Asia are obviously to be lagging in that trend.

If you explore homes in Europe, you will find very small number of incandescent bulbs, and quite common that lamp will be on a dimmer. “In Western countries of Europe, consumers are more eager to pay additional money to enhance a green lifestyle. They are keen on looking for LED light bulbs than any other country in the world.

Friend of mine who is the senior engineer for LED manufacturer asked me what about the maximum light output that we can obtain form the LED. And If that LED lamp can last that long without breakdown as it was listed as one of the sales slogan of 50,000 hours?

In general, higher junction temperature and higher current will mean lower life. There are several failure modes on LEDs, but which one is most likely depends on the architecture of the particular lamp.

“In theory, physics says you could get about 230 Lumens/Watt at perfect efficiency. Most products today are in the neighborhood of 80-90 Lumens/W, and we have cool white lamps [emitting light with a higher color temperature] in the laboratory producing about 130-160 Lumens/W.

Certain users prefer slightly warmer light, and the theoretical perfect efficiency would produce only about 200 Lumens/W at the lower color temperature. The major players had something in the neighborhood of 150 Lumens/W in the lab. But these are hand-built devices. Commercial available device are in the neighbouring of 70-80 lumens/W.

As there is still a need for certain technology breakthrough for higher efficiency say commercial available 200 lumen/W LED. LED should be made at a cost of say 30% of the current LED., Then with these added feature of lumen light intensity per dollar is least 5X better than the current available LED lamp solution.

Then that will be the time for public to accept the LED light bulb to be a standard for domestic application, at that time I think your Incandescent Lamp will be come kind of collectible item and we can only seeing these at Museum!

When that day will be? I think that is 2012.


*1
There are three ways of producing high intensity white-light using LEDs. One way is using RGB LEDs. One is to use individual LEDs that emit three primary colors– red, green, and blue, and then mix all the colors to produce white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.

CCFL, RGB and White LED TV Back Light system

What is the major comparison between CCFL, RGB LED and White LED back light for LCD TV?

CCFL

CCFL has certain mercury content and LED Back Light is mercury free.
LED back light has a wider colour Gamut than CCFL
CCFL has high Power Consumption and LED backlight has a higher Luminous Intensity.

RGB LED
It is true that RGB LED BLU offers a wider color gamut, but image quality becomes more likely to degrade if the color gamut is extended more than necessary. It will cause the display to render incorrect colours.
RGB LED back Light can have a Local dimming which enable to have extra Dynamic Contrast up to 2,000,000:1

White LED
White LED BLU benefits are more efficient in boosting image quality.
White balance fluctuates more easily for RGB LEDs
Cost lower than RGB LED BLU
Lower manufacturing costs
Simpler backlight control system
LED Back light can work with Impulsive Driving that enhance picture speed and movie will appear smoother. We can reduce spatiotemporal integration time by inserting a black frame between image frames.

How we should drive a LED?

LED works with a linear current control or Constant current control because of the following reasons:

The Current has a non-linear relationship with the Relative intensity of the LED.
The variation of the Current will change the dominant wavelength of a LED.
So it is necessary to maintain a constant current thus to ensure constant LED colour.
The current control supply can be all SMT components; this high power resistor is eliminated. This reduces the assembly complexity. Again this will give a cost saving.
Reduce power dissipation at high temperature, high supply voltage, and lower LED forward voltage condition. (as compared to a resistor drive)

Constant current source will give better, more uniform appearance, and allow it to meet a tighter tolerance specification.

Two technologies can be considered in designing the LED driver: the first one is linear current control driver; the second is switch mode current control driver.
The Linear current control or constant current source is commonly used due to lower cost than the Switch mode current control driver.

LED Constant Current Source
A constant current source for LED is usually consisting of a small integrated circuit and several external components, the constant current configuration serves as a relatively inexpensive LED driver solution. The drive current is typically set during design by the use of an external resistor connected between ground and a single pin of the IC chip package. The circuitry is compact enough to fit directly on the circuit board along with the LED lights in the array. As the voltage fluctuates during operation, the constant current source will do the job to compensate and to maintain a steady current output for each of the LEDs within the array. Lighting systems equipped with multiple LEDs may operate from several redundant constant current sources. In such a case, the components are located upon the same circuit board and share a common power supply. Individual sub-circuits will appear to operate as one.

Junction Voltage Drop Variations
Another common cause of voltage fluctuation is the result of varying junction temperatures within the LED. As current passes through the LED, the junction temperature will begin to increase. This increase in temperature causes the forward voltage drop across the junction to decrease. Reductions in forward voltage lead to an increase of total current flowing through the LED light. The increase in current causes an increase in temperature. This continuous cycle can lead to catastrophic failure unless the current is limited. High power LEDs are extremely susceptible to variations in forward voltage. The constant current source provides an ideal solution in order to achieve a reliable circuit and prevent risk of thermal run away.

Manufacturing deviation
Imperfections during the LED manufacturing process can cause individual LED characteristics to vary somewhat drastically. The binning process relieves this dilemma by categorizing LEDs according to key characteristics including luminous intensity, spectral wavelength, and forward voltage drops. However, LEDs common to a voltage bin typically do not present identical forward voltage drops. Furthermore, the difference between the forward voltages of dissimilar bins may be dramatic. Some light emitting diode manufactures may not even offer binning according to forward voltage. As forward voltage differentials will cause drive current differentials. The solution is to apply the constant current source in order to compensate for such deviations caused by the LED manufacturing process.

Simplified Circuitry

Some engineers consider using simple resistor driven circuitry as a bad practice. This is mainly because forward currents can vary as the forward voltage across the LED and junction temperature changes. Deviations during LED manufacturing cause forward voltage drops to vary, which results in dissimilar drive currents. Varying source voltages often associated with automotive applications can also lead to current fluctuations. Although never recommended in lighting systems equipped with high power LEDs, simple resistor driven circuitry does not present such a negative impact when utilized within circuits containing traditional LEDs. However, one should be very cautions employing this technique! Typically the lower power devices such as a 100 mW LED, to not require advanced drive circuitry.

Although advanced circuitry may present numerous advantages when used in conjunction with lower power LEDs, the overall cost efficiency is typically not one of them. Heat dissipation is much less and forward currents only vary slightly in a properly designed circuit.

Considering the benefits cost efficiency are up to one hundred times greater with simplified drive circuitry, it is clear why such small variations in forward current become insignificant.

Selection of appropriate resistors and proper circuit architecture, help assure operation over a minimal current range even as the voltage variables are applied. It is very important to perform resistor calculations using the typical forward voltage drop as specified in the LED datasheets, but also while considering the minimum and maximum specified voltage drops. By doing so, it becomes easy to see how much or how little the forward current may vary between LED lots.