Posts Tagged ‘Solid-state’

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 my previous entries regarding the Cree LR6, I’ve noted the good and bad sides of the product in some detail. I’ve noted my dissatisfaction with the brightness of the diffuser, which has caused me to first apply plastic trim rings to add a little cutoff, then later, to simply not turn them on. Dimming performance over the years has been disappointing as well. No dimmer I have found has dimmed them satisfactorily, most cause them to flicker. The latest from Lutron, designed specifically for LED/CFL sources, did not fix the issues, so I simply gave up. Rather than remove these expensive retrofits ($65.00+ each), I chose to do what many of us do when caught in a  quandary – stopped using them at all. Estimating these were not used more than an average of 1 hour a day for the last 4 years, total operating time is less than 1,500 hours. I’ll give them 2,000hrs, assuming that when they were first put in place, I used them more than I did as we grew tired of their glare and flickering under dimmer control. (more…)

Like the previous reviews of light meters, I am restricting this review to affordable temperature meters I have direct experience with in actual project work. Anyone who works with or applied LED technology should consider investing in some form of reliable temperature meter to test results of either products in development, or product performance in the field. The Achille’s Heel of solid-state technology is its susceptibility to failure and degradation from operating at high temperatures. This extends beyond the LED into the driver and power supply components, which are often placed under stress from fixture packaging or location near heat sources. The first issue that a manufacturer will raise when facing a field failure, will be the temperature the fixtures were operated in, either caused by the product design, or the physical application, heat kills LED products. That said, just like photometric test equipment, laboratories and large engineering departments will spend many thousands of dollars on test gear, and calibration services. That’s great if that is the focus of your business. For the rest of us, especially those in small business, the costs of test equipment must be weighed against the myriad of other tools and expenses. So, the question becomes, can one keep the costs low and still get reliable results. The following is an attempt to provide some insight into this, and show solutions I have found to be reliable after several years of using various products with varying degrees of satisfaction. (more…)

For anyone interested in saying hello in person, to knock ideas around, or just tell me what you think of things, meeting up at a conference is ideal. Since I try to bring original content to each venue, the time it takes to put a presentation together is enough that I usually limit the number of presentations to 3-5 a year. This year is about over, but I do have 3 more to go on the schedule, for anyone interested. (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…)

After reviewing a range of different metering choices in actual use, I compiled a summary of findings, as well as my own personal subjective ratings of features and overall utility as a lighting professional. This chart is the collection of all findings in a simple comparison table for those who find this useful (like me): (more…)