What is a LED Tube Light?

Abdul Lateef, CEO of Plasma-Therm, a maker of plasma-enhanced CVD (PECVD) tools, discussed the demand for better data management from LED manufacturers. He provided an example of how in-situ metrology is helping to automate the process. "We have equipped our PECVD tools with optical emission interferometry which uses the light from the plasma to monitor film thickness," he said.

Mike Plisinski of Rudolph Technologies also discussed the theme of metrology and yield management methods. He said "Epi engineers have little visibility into the impact of epi on downstream LED processes." Plisinski suggested a concentration of process-control resources at the epitaxial process level.

LED manufacturers can use automatic defect classification to classify defects into type and cross-reference this data with yield management to separate harmful from nuisance defects. "We’ve seen cases where certain defect types, regardless of size, always impact yield, whereas other types do not," said Plisinski. He said that inspection recipes can then be tuned to detect the critical defects. He also emphasized that the investment in process-control tools should scale with production capacity.

Next, Dan Scharpf of Labsphere talked about optical testing of LEDs. He said that one of the challenges in LED manufacturing is identifying which process steps impart the greatest variation in lumen output and color of the LED. He also said that more LED manufacturers are interested in performing LED testing at elevated temperatures.

He stated that thermal control is a challenge, whether the test is performed at the wafer, die or module level. Scharpf added that testing at elevated temperatures will increase test times because an equilibrium condition must be achieved. He further warned that if an LED undergoes self-heating, operating wavelength is likely to shift and measured flux can change significantly.

Geoff Gardner of Dow Corning talked about innovations in silicone technology as applied to LEDs. Silicone is perhaps best known for its use as an LED chip encapsulant. Garner said the company has developed silicone with a higher refractive index specifically for high-power LEDs. "Any LED above 0.5 watt is going to require a higher-refractive-index material capable of withstanding high operating temperatures," he said.

Silicone is also used for injection-molded secondary optics such as total-internal-reflection lenses. In the case of remote-phosphor optics, silicone can withstand higher temperatures than the prevailing material used today, a polycarbonate. Finally, thermal-interface materials made of silicone can be screen printed and cut to virtually any shape to provide stress relief, shock dampening and/or heat transfer in a variety of LED lamp and luminaire applications.

Western leaders repeated their call on Monday for Russia and China to support a strong United Nations Security Council resolution to end the violence in Syria, where scores of people have been wounded or killed daily. The appeal came during a high-level meeting on the impact and opportunities of the Arab Spring, which was overshadowed by the Syrian crisis.

United Nations Secretary-General Ban Ki-moon led the call, telling the 15-nation Security Council it is essential that the organization's most powerful body speak with one voice, particularly in light of the continued "shameful operations" of Syrian President Bashar al-Assad's army.

The United Nations and the Arab League recently appointed former U.N. chief Kofi Annan as a joint special envoy on Syria.  Annan traveled to Damascus recently, holding two days of talks with Assad. 

Ban said his predecessor conveyed "concrete proposals" to Assad, urging him to take steps to immediately end the violence, address the humanitarian crisis and begin a peaceful, inclusive, Syrian-led political process.

"I add my voice to that of Mr. Annan in urging President Assad to act swiftly, within the next few days, in response to the proposals put forward by the Joint Special Envoy.  I appeal to the Security Council to unite strongly behind ending the violence and supporting Mr. Annan's mission to help Syria pull back from the brink of a deeper catastrophe," Ban said.

Russia and China have used their Security Council veto twice during the past five months to block action against Damascus, saying that the West and some Arab states are seeking regime change in Syria.

U.S. Secretary of State Hillary Clinton said the Security Council's silence is not an option in the face of a government's massacre of its own people, and she urged Moscow and Beijing to support action against Syria.

"We believe that now is the time for all nations, even those who have previously blocked our efforts, to stand behind the humanitarian and political approach spelled out by the Arab League.  The international community should say with one voice - without hesitation or caveat - that the killings of innocent Syrians must stop and a political transition must begin," Clinton said.

In a rare rebuke for a close ally, Russian Foreign Minister Sergei Lavrov said Syrian "authorities bear a huge share of responsibility for the current situation."  He said Moscow wants to see an immediate end to the violence, a cease-fire and access for relief workers.  But Lavrov warned against international action that could escalate the crisis.  He is heard here through a translator:

"Making hasty demands for regime change, imposing unilateral sanctions designed to trigger economic difficulties and social tensions in countries, inducing the opposition to continue its confrontation with authorities instead of promoting dialogue, making calls in support of armed confrontation and even to foreign military intervention - all of the above are risky recipes of "geopolitical engineering" that can only result in the spread of conflict," Lavrov said.

At the recent Strategies in Light (SIL) conference in Santa Clara, CA, Chung Hoon Lee, CEO and founder of Seoul Semiconductor, provided a keynote address that discussed some of the principle behind the Acrich2 AC-LED modules, which operate directly from AC line voltage. In addition, two of the company's AC-LED modules have been recognized under UL's Component Recognition Program.

Lee described Acrich2 modules as being suitable for many residential and commercial lighting applications where the main source of available power is AC.

Speaking on the complexity of LED lamp design, Lee showed a chart that compared Acrich2 LEDs to DC LED lamps manufactured by five other companies (listed as Company A through E). Holding up the electrolytic converters and other components of the LED lamps, Lee asked "What is this?" His answer, "This is junk," received applause from the audience.

Lee stated that these additional components can cause LED lamp failures. In tests, Seoul Semiconductor determined that many of the other LED lamps reached temperatures of 70C to 82C during operation. The CEO stated that even though companies typically claim lifetimes of 35,000 or 50,000 hours for their lamps, that lifetime can be reduced to 10,000 hours or less due to these operating temperatures. Moreover, tested power factor of the LEDs ranged greatly, from 54% to over 90%.

Lee said the Acrich2 design can provide a better power factor and less total harmonic distortion. "We can reduce the heat sink, protect the environment and provide more design freedom," he said.

Acrich AC-LED modules use an integrated circuit to provide power conditioning and circuit protection, necessary functions with AC LEDs. In recent weeks, Seoul Semiconductor has made several product announcements in the Acrich2 family including a Linear Module designed as a fluorescent replacement.

The UL recognition is designed to help customers using the modules to more easily obtain UL listing of their replacement lamps and luminaries. For the UL testing, requirements contained in the UL 8750 standard were used. The two modules, SMJEA3011220, an 8W module that produces a minimum of 500 lm, and the SMJEA3012220, a 13W module that produces a minimum of 800 lm at a 120V (shown), are designed for replacement lamps and similar applications.

We are a year away from the mayoral election and it is already clear that the Tube is going to be a huge issue.

This morning the accusations and counter accusations have been flying.

Labour and Ken Livingstone issued this press release - focusing on Tube performance and in particular the problematic Jubilee Line upgrade:

New figures show Tube delays getting worse
 
Following the publication of new monthly Tube performance figures by Transport for London (TfL) which show delays increasing across the underground network Ken Livingstone and Val Shawcross AM have called on Conservative Mayor Boris Johnson to, 'get a grip of the daily delays and disruption on the tube'.

Vibe LED tubes from ANL Lighting provide an ideal alternative to fluorescent tubes as they are a more efficient and environmentally friendly way of lighting.

LED lights offer reduced operating costs over their long life thanks to their efficiency. LED does not contain the harmful mercury and phosphorus that is found in fluorescent lights, which makes LED lights even more environmentally friendly.

Replaceable adapters are provided on all Vibe LED tubes lights, achieving a projected lifetime of approximately 80,000 hours, helping to save an extra 50% on replacement costs.

Phillip Hill, Vibe Director, explained, “When the driver eventually fails, instead of having to replace the entire LED tube, you need only to replace the adaptor. This makes the Vibe LED Tube the most economical and cost effective option for replacing standard fluorescent tubes.”

One key advantage of LED tube lighting is that it will not flicker like fluorescent tubes. Flicker and glare can impact learning and the ability to concentrate while also causing headaches. Although humans cannot see fluorescent lights flicker, the sensory system can. LED tubes operate a constant colour output resulting in no flicker.

LED tube lighting is ideal for used in schools, offices, retail stores and other applications where the consumer is looking for a long-lasting, green alternative to fluorescent lighting.

Vibe LED tube lights are available in a wide range of colour temperatures and wattage options. Colour options include; Warm White, Pure White, Daylight White and Cool White, while the length and wattage options include; 600mm (9w), 1200mm (18w) and 1500mm (22w).