Integration of LED Lighting into Mainstream Life

The European Union is phasing out conventional incandescent light bulbs prior to its ensuing ban in 2012 and is moving towards high-brightness light-emitting diode (HB-LED), also known as solid state lighting, in order to reduce net carbon dioxide emissions, since these devices consume 80 percent less energy. According to Reuters, about 16 billion conventional light bulb fixtures have to be replaced globally in the coming decades with LED lights. Researchers at consultancy iSuppli expect the LED market to continue to grow despite the slow global economic recovery, estimating that in 2013, sales from LEDs globally will be approximately $15 billion. 

"Warm" lighting generated by LEDs is more expensive than "cold" lighting. Colors based on the red area of the color wheel appear in general to be warm and inviting. On the other hand, colors on the blue side of the color spectrum appear to recede from us and are considered cold colors. It now costs about $46 to deliver 1,000 lumens (unit for light intensity) of "warm" light, compared with $25 for the "cold" light variety. By 2015, the cost of "warm" LED lights is expected to fall to $4 per 1,000 lumens versus $2 for "cold" lights, according to estimates from the U.S. Department of Energy (DOE). In contrast, it costs 29 cents per 1,000 lumens to produce incandescent globes. The DOE expects the cost of producing LEDs to decline below that of compact fluorescent lamps in about 2013, but still be more expensive than an incandescent bulb.

LEDs are most frequently being used to replace conventional bulbs in restaurants, entertainment centers and hotel lobbies, where they can take on a decorative effect due to their ability to change colors. Most mainstream operations have yet to switch due to the high cost.

Lighting products have historically been reliable, but as electronics-rich (compact fluorescent lights) CFLs began to replace incandescent bulbs, consumers began seeing the products' early failures often due to poor product selections. CFL lifetime is reduced when users turn them on and off frequently, and also are sensitive to airflow, which gauges the flexibility of applications. Other failures are due to low-quality lights in the product design, the components in the design, or the units' packaging methods. The electronics components surrounding the fluorescent tubes rather than the tubes themselves are often the causes of failures. As residential, commercial, and industrial lighting begins to shift towards solid state technology, there are obvious concerns of customers with regards to short lifetimes and reliability problems.

Product lifetime and product reliability are two different issues. First, lifetime refers to the length of time an end user can expect a product to function, whereas the word reliability refers to how many products per thousand a user can expect to fail in normal operation during their expected lifetime. HB-LED device manufacturers often quote lifetimes of 50,000 hours or more for their products. However, specifying lifetimes for HB-LED-based lights is more complicated than using the lifetime for an HB-LED because the lighting unit comprises an LED driver, which is a power supply whose lifetime and reliability vary with respect to its internal components. Capacitors usually have shorter specified lifetimes than the other components in the driver circuit and can be the limiting factor.

An upcoming article will focus on the details of breakdown mechanisms in these devices, impacting lifetime and reliability, and how the industry is addressing the issue.

"Photo credit- www.feret.com : Representative LED lighting on commercial property"