Tuesday, August 16, 2011

LEDs as task lights

Lost in the Shadows

For me, using LEDs as task lighting is still a developing technology. I am very happy with the lumen output that we are starting to see now, along with the color quality. I personally lean towards a warmer color tone that is close to that of incandescent (2700° Kelvin), but many others do prefer the slightly cooler color temperature like that of halogen (3000° Kelvin). Still others who are doing fine detail work, such as jewelry making, like to have a color temperature close to that of daylight (5000° Kelvin).

A single LED may not produce enough illumination

Where I am seeing room for improvement is how to deal with the creation of multiple shadowing when more than one LED source is used in a task light. Those fixtures on the market with a single source LED act like a single source incandescent or fluorescent. One source equals one shadow, which is what we have all grown up with and is what we are used to seeing. But a single source LED may not provide enough illumination for many people. When multiple light sources are used, as we are seeing in the LED task lights that are coming onto the market, you get a shadow image for each light source. The more individual LED diodes you have in a fixture the more shadowing you get as well. When reading a book or a magazine this really isn’t an issue, but if your hand, pen or pencil comes in between the light source and the work surface it can have a lot of disconcerting shadowing with which to contend.

The individual LEDs create multiple shadows

Although I am not lighting fixture designer, per se, I think of myself as an informed consumer who is constantly testing what is available out there on the market. My suggestion to the task light designers is that when multiple LED sources are used then some sort of diffusion material, in the form of a lens, will help ameliorate the problem. As individual LED sources become stronger and only one source is used, then shadowing will no longer be an issue.

Many manufacturers of recessed LED fixtures have seen that this multiple shadowing was an issue and have produced fixtures with an integral diffusion lens. It would be a good idea if the manufacturers of LED task lights would take a look at what the recessed LED fixture manufacturers are doing and see how they can incorporate the addition of a diffusion material into their products.

Manufacturers like Cree use a lens to hide the LEDs and eliminate multiple shadowing

I still am a very strong advocate of using LED sources for task lighting. I would just like to see the next step in refinement; so that when people make the investment they are getting something that they can live happily with for the next 16 or 17 years. Since LEDs last for so darn long I want to make sure that my love will last as well.

Wednesday, August 10, 2011

The Future of Light Sources…What's on the Horizon?

Advances in light sources had been in stasis for a long time. It wasn’t until the introduction of the improved compact fluorescents and warmer colored LEDs that we really started seeing a shakeup of the status quo. Incandescent sources have been around for more than 100 years and the first fluorescents made their way into regular usage in late 1930s. Even LEDs have been around since the 1960s, although at that time they were only available in red, yellow, blue and green.

Warm colored LED and CFL sources are being seen more and more in California bathrooms and kitchens due to California's Title 24 requirements.

The GU24 lamp is small and dimmable.

Keep your options open
As I see it, the future of lighting will not be determined by one light source alone: there will always be a need for various sources to provide the types of light that we want and need. For one thing, I don't think that incandescent lamps ("lamp" is the industry term for "light bulb") will totally be eliminated as some people are predicting. I believe that manufacturers will work hard to create higher efficacy versions of the incandescents we all know and love. Maybe people who suffer from migraines, as a result of exposure to fluorescent lighting, will be issued medical incandescent cards, like medical marijuana cards.

Not your father's fluorescent
I see that fluorescents are evolving as well. First off, there was the introduction of the GU24 lamps. Their socket and lamp assembly fits very well into the space normally taken up by standard incandescent lamp. So now many manufacturers are offering many of their decorative fixtures that use a GU24 alternative. These lamps can be dimmed down to 70% with a standard incandescent dimmer.

CCFL's like these from Litetronics.com can hide inside a standard A-lamp, G-lamp and B-10, with clear or frosted glass envelopes

Then there are the CCFLs (cold cathode compact fluorescents) which have a much fuller range of dimming than standard CFLs; and are available in warmer color temperatures than what seems to be the standard issue 2700° Kelvin. The truth is that most people do not operate their lamps at full blast which would be in the 2700° Kelvin to 2800° Kelvin range. They instead dim them down to 2200° Kelvin to 2250° Kelvin. Having lamps available that are the color of dimmed incandescent will make the transition from incandescent to fluorescent (and LED) much more palatable to the general public.

The other big change in fluorescents is the availability of a fluorescent lamp that is mercury-free. This will make a lot of people happy. I have mentioned the mercury-free dimmable lamp by the VU1 Corporation before, but it doesn't hurt put their name out there again because I think the general public and the lamp making industry as a whole should take notice.

Making room for LEDs
LED reading lights are one of the many inventive items coming onto the market. I am very excited about all the possibilities that LEDs offer. While they may not be quite in their infancy, they are still in the toddler stage. Every six months LED products are improving. They are providing better lumen output, better color rendering, better color consistency (a.k.a. binning) and are becoming available in a wide variety of fixture types. I think the biggest challenge for the LED market as a whole is dimmability. People do like to control their light levels. Companies that make LED components and light fixtures are only just now talking to the companies that make dimmers and dimming systems. It would be a wonderful world if all LEDs dimmed the same way and could be controlled with a variety of products from regular wall box dimmers through to home integration systems. We are not there yet, but I am hopeful.

This LED A-lamp (eco-story.com) becomes yellower in color when dimmed.

Until very recently, I could state that LEDs like CFLs do not get warmer in color when dimmed. Now at least one company, I've been made aware of, can do just that. The Eco-Story company has introduced the Eco-Hybrid A- lamp that does actually get warmer in color temperature as you dim it. It's not perfect. The transition between colors is not perfectly smooth, but like I said before… I'm ever hopeful.