Archive for the ‘General SSL Commentary’ Category

There remains an issue of flicker and its issues that has been drawn out by a lack of action on the part of our standards and professional organizations. The topic of flicker has been turned into years of discussion, consternation, regurgitation of old information, tests to prove what has already been known for years, and avoidance of conflict. One of my best selling products from the Lumenique Product Center is the Flicker Machine, as simple device for visually detecting and confirming that visible flicker exists within a space or from a source, indicating there is a desire of individuals to know more. I presented a bit on this device and its use here some time ago.

This little spinning wheel tells the story. If you see banding and colorful rainbows, the lights are a flickerin'

This little spinning wheel tells the story. If you see banding and colorful rainbows, the lights are a flickerin’

I have invested my personal time exploring this topic, including membership in the IEEE 1789 committee addressing the risks of flicker, presentations at DOE and other conferences, working with various manufacturers on their line voltage, non-driver products, and personal testing, experimentation and actively living with and under AC LED products.  After more than 6 years of this, one simple question surfaced for me.

If DC and high frequency (>2,000Hz) PWM driven constant current LED solutions produce no visible flicker, why consider a source with greater flicker presence? (more…)

There are many subjects in lighting, specifically in the universe of solid-state lighting, that need to be actively discussed and openly debated. Issues such as qualitative issues (color, color accuracy, glare, brightness, illuminance levels, etc..) over quantitative (lumens per watt), or the discussion of blue light content, or scotopic v. photopic, or supplier issues, or even the problems of being a small fish in a pond filled with big bloated corporate fish and a governmental agency who believes itself now a lighting expert… These all require active dialog to be resolved and grow understanding.  Too many times, the discussion of important topics are held in little rooms, hidden from view, with conclusions drawn, recommendations and regulations written – to be handed down like tablets from the mount, for us all to simply step in line and accept as fact. We have far too many instances of white paper writing scientists issuing their narrowly focused findings through their myopic peer groups, to be used as swords and weapons against the unwashed and unknowing masses. I find the creeping movement of lighting away from its roots as a human experience enhancing art-form into the hands of marketing zealots, narrow minded PhD’s working in their corporate labs, and federal or state agencies with agendas to follow outside our need to know… well, disheartening and disgusting. (more…)

In a recent article published in Architectural SSL on the topic of blue light content of LEDs, I attempted to present the discussion of blue light from the perspective of those raising concerns about blue light hazards against known and practical objective knowledge on the topic. The article covered the gambit of concerns, from retinal damage concerns to melatonin levels in occupants, from both sides of the argument, as there are those who dismiss this as a non-issue out of hand. The article also forwarded two conclusive suggestions. First: The research on this specific topic, as it relates specifically to LED light sources, is a little thin. Second: For those concerned about blue light content, selecting LEDs of a lower CCT and higher CRI delivered the lowest blue light content. Whether or not this is the best choice for visual acuity was not the subject of the article, nor was it suggested as the best solution overall. There is a great deal of research supporting the concept of high CCT light for enhancing human visual performance. Much of this was completed under light sources other than LEDs, so there is no caveat included that states anywhere that blue light content of LEDs is at acceptable levels, or of no concern. (more…)

08285I have a fondness for the halogen lamp. From the little 20W bi-pin 12V burners to the 500W double ended monsters, the combination of light quality, simplicity, toughness, light density and versatility filled a special place in the hearts of lighting designers for decades. While there were also  larger iterations of the technology reaching 20,000W, even the most halogen crazed found them to be a bit over the top, setting them aside for special applications. In my own experience, the 20W through 75W 12V burners, 15W through 65W MR16, 35 through 50W PAR36 and 75W through 250W mini-can line voltage lamps hit the spot for a wide range of focused and unfocused lighting product designs. For my personal portable lamp works, the low voltage burners, MR16 and the PAR36 lamps were my favorites. I could create live-structures (where the fixture acted as conductor) using remote 12V power supplies, allowing sculptures to be simple to the extreme.

This simple bridge design was created using building and armature wire, a PAR36 halogen lamp, and a ball bearing counter weight.

This simple bridge design was created using building and armature wire, a PAR36 halogen lamp, and a ball bearing counter weight.

When LEDs arrived on the scene in the late 1990’s, I caught a glimmer of what was to come. By the year 2002, it was obvious that solid-state would be delivering something new, and that the properties of the source technology shared a great deal with the halogen lamp from a lighting perspective, with a huge advantage – far less heat, much tougher and resistant to impact, and very long lived. The only issue was, color quality was initially poor, consistency from LED to LED was awful, and light output per individual LED device was pathetic. This required designs utilize a number of LEDs mounted to circuit boards, wired to drivers that were clumsy at best. The complexity of LEDs in the earlier stages were compounded by the lack of available components, which meant one-off application of the technology was out of reach for anyone not up for custom electronics design. (more…)

To set things off on the proper foot – I do not like complexity when it is not necessary. I’ve noted many times that if energy were free and maintenance was not a consideration, the perfect light source is the tungsten halogen lamp. This technology delivers a very attractive white light, is very easy to control, provides optical focus, and is as simple as it can get. The low voltage versions of this technology are equally attractive, accepting that transformers were a horrible thing to tag onto an otherwise neat little light source. I have made hundreds of lights using halogen lamps, mainly 12V versions, starting back in 1985. It was my go-to light source. I still have boxes of transformers and sockets, acquired over years of making lights for myself and others.

Applying LEDs in efficient lighting designs is no more complex than use of any other source, just more productive.

Applying LEDs in efficient lighting designs is no more complex than use of any other source, just more productive, and attractive than CFL or other conventional “efficiency” improving sources.

That said, there is no escaping that energy is an issue, and maintenance is a pain. The cost of operating halogen technologies is simply impossible to bear. This is why we have HID sources with all their ugly liabilities, and the fluorescent lamp.  While I get HID technology as a giant super-power halogen device, it has always been a clumsy, heavy, messy engineering gadget that sets aside the art of lighting for raw lumen energy. Fluorescent lamps have are a source you are forced to live with, in an uninspired, just-get-lumens-in -the-box sort of way. There is very little to love about their scale, lack of focus-ability, ballast hardware, delicate tubes, and ghastly glow. I’ve specified millions of these lamps into existence, wishing every time there was a better way. I never made a single art light using fluorescent lamps, not because itsn’t possible, but because I never liked them enough to give them that part of my time.

The emergence of solid-state lighting, specifically LEDs, hit me in two ways. One, I get the small controllable source I had with 12V halogen. Second, I get the efficiency and raw lumen potential of fluorescent that made it indispensable. Because of this, the last time I made a light using halogen technology was in 2004, and that product was converted to an LED sources in 2006. For my own use, every halogen light I made from 1993 to 2004 still in use around the house, has been converted to LED. Every new fixture made since 2005 has incorporated an LED light source, without exception. I do not use retrofit lamps. I either tear down and rebuild products to utilize LEDs properly, or design them around LEDs in the first place. (more…)

The Replacement Dichotomies

Side One: It is acceptable, if not desirable, for LED luminaires to be replaced at the end of their service life. This is a common position among a wide range of LED product manufacturers. They make the case that extracting performance and costs from LED products requires a level of integration that cannot be accomplished using modules. This further forwards to concept that modules restrict design freedom, that integrated products are free to create light source forms to suit the intended end-product design, without restriction of standardized sockets or modules. Therefore, it is proposed, that the highest performing SSL products will be integrated units, replaced at the end of their life with the next generation of even higher performing product. The model often used to illustrate this approach is that of televisions, where the entire units are replaced, rather than serviced, with newer generation products.

Side Two: The single most active market in solid state deployment is that of the direct lamp and fixture replacement space. This includes screw based lamps made to imitate the light output and distribution of obsolete technologies, and extends now to bi-pin linear forms to replace fluorescent sources. Oddly enough, the one lamp form that is not addressed, is the one most universally despised in commercial and residential markets alike – the plug-in CFL lamp – but let us not be distracted by this obvious and blatant oversight.  This replacement lamp direction appears to make the statement that the existing infrastructure of sockets is not replaceable, that demanding building owners and end use customers to replace existing fixtures is a burden beyond acceptable limits. This also forwards the concept that the existing socket forms within compromised products, is acceptable, regardless of its severe negative impact on SSL product performance, design freedom and appearance. (more…)


In an effort to create the highest possible performance in a portable lighting product, assembling the right combination of components is essential. Obviously the process begins with an efficient LED suited to the lighting effect desired. The LED must then be matched with an efficient driver. Finally, the driver must be fed power from an efficient power supply that converts incoming AC line voltage to clean DC power. Efficiency is generally found in matching the load of the LED to a driver designed for that load with no necessary over-capacity. Then, mating the driver to an efficient power supply matched in size to the driver’s operating load is necessary to produce the highest combined efficiency. (more…)