Posts Tagged ‘LEDs’

Opening Remarks

Modern human existence, as we all know, is primarily carried out indoors. Exposure to natural light is also highly seasonal, even when we avail ourselves of the opportunity to include it in our regular activities. At most, for many in the northern continents, natural light varies from being too feeble to be of value, great enough to be of value, but with outdoor temperatures too cold or hot to tolerate with regularity necessary for good health, or so highly variable throughout the year, that reliance on it as a natural part of our existence is impossible. Further, as we all age, subtle changes take place over time that are not always noticeable at their early stages, but become more of an issue as the years pass. As a result the light we are exposed to indoors, is the bulk of our photonic existence. (more…)

The recent press release announcing Philips, Cisco, et al,  joint venturing to deploy and build Power over Ethernet (PoE) networks in lighting is going to fuel this discussion and create a stir, without a doubt. In the press release, all the current hot buttons were pressed with vigor, from App controlled lighting using smart phones to ties to the Internet of Things (IoT). The picture painted by this release, presentations on this topic, and other articles floating about, indicate a future where lighting breaks its bonds of wiring to be free to serve us all in magical, never before realized new ways, using less energy through magic DC power, finally severing us from the drag of AC power. It’s certainly got folks talking.

At the recent LED Specifier Summit in Chicago, I was asked by no less than 8 people what I thought about PoE, and whether it was going to be the next big disruptive innovation to strike lighting. Concurrent to this were phone discussions with technology providers and fixture manufacturers, asking similar questions. It was hard not to think that something was going on, as everyone seems to be all quivery about it. The problem is… I am not so sure what all the fuss is about, and whether anyone is really thinking this through. I like the concept of a distributed network style, low voltage DC lighting infrastructure. It solves fixture design issue, and presents intriguing possibilities for integrating controls, lighting and the IT universes together in ways our current system of isolation-in-high-voltage simply cannot easily address.

Advantages Impossible to Ignore (more…)

I have an ongoing project in creating various lighted magnifiers to see small items, inspect surfaces, check tool edges, or just read the micro labels printed on electronic parts or other components. In 2010 I presented one of these gadgets, specifically a device for reading drill bits, using LEDs and a 9V battery. This time around I wanted to create something with more flexibility, more light, greater magnification and a larger aperture. The concept is pretty straightforward, using a light gathering lens with an integrated ring light component. It delivers over 1,740 Fc on the target, which makes seeing the tiniest details readily visible.

A multipurpose magnifier light ring tool.

A multipurpose magnifier light ring tool.

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Welding creates a serious challenge to visual acuity. The light emitted from gas and arc welding is intense, and contains high levels of both UV and IR light in wavelengths harmful to the human eye. For this reason, welders (myself included) wear helmets and goggles that utilize filters to reduce brightness, strip away the harmful wavelengths, and protect us physically from welding splatter, which is very nasty. Unfortunately this seriously compromises visibility of the welding task and its surrounding. While the arc itself illuminates the surrounding, the contrast between the arc itself and the area around it is so great that this affords little clarity. When smoke and splatter are included, most welding is done within a very poor visual field. In some case, it is done almost completely blind.

The concept is to use narrow spectrum green light, in this case 530nm Green, to more efficiently deliver visible light through welding glass filters. This increases intensity in the area of the task.

The concept is to use narrow spectrum green light, in this case 530nm Green, to more efficiently deliver visible light through welding glass filters. This increases intensity in the area of the task. It is very difficult to photograph exactly what one sees through the darkened welding glass, and impossible when an arc has been struck.

Most welding glass passes light in a narrow green centered bandwidth, which is why the view through them is green, to the point of being monochromatic. That means most of the light from any task light used that generates white light will be filtered out along with the welding arc emission. That seems inefficient and reduces the effectiveness of the lighting system to the point of being essentially useless.

To address this, over the last three years, I have been working on a task light that delivers a narrow spectrum green light, centered on the emission of the welding filter glass itself. This means that 100% of the light from the task light will come through the glass – a much more efficient approach. You can download a white paper WIP of my findings and concept at: http://www.lumenique.com/New_Lumenique/Files/Narrow Spectrum Welding Light KLW.pdf

An early test mule using three 5W green LEDs and medium narrow optics to create intensity.

An early test mule using three 5W green LEDs and medium narrow optics to create intensity.

This is a work in process. However, so far, with the same energy applied to an identical white light source, vs. a green light source, the amount of brightness visible through the welding glass is doubled.

There have been a few interesting discoveries in this process:

  • The early test mule (shown in the image above), utilized optical reflectors to intensify the beam pattern. I was hoping to amplify the effect of the focused task light into the visual welding field. This actually proved to be less useful than it might look, due to the creation of harsh shadows from the welding gun or torch, so later models have reverted to a more diffused, softer beam pattern, which reduces these effects.
  • LEDs act like low efficiency photo-voltaic sources when exposed to high intensity light. This creates voltage back into the driver during welding work. For the most part, this is not an issue. However, with a few drivers I have employed, this effect causes internal failures (not fully explained). I isolated the voltage from the welding area, electromagnetic effects, and all other factors, before testing the theory that some drivers cannot deal with this by applying a small external voltage to them in operation, which duplicated the failure mode. Now I test all drivers under a welding arc, on aluminum and steel substrate (each emit a different spectral power state), to insure this does not create undesirable results.
  • When gas welding under the green light, I find the appearance of the flame kernel (main heat source) more pronounced, which appears to be from the increased intensity of the surrounding field. This is a happy development, as it increases visibility of the location of that heat source to the weld zone. There is also an enhancement of the colors seen in the weld pool to a small degree I am working toward intensifying further.

I will be working on this more as time passes, so will update this entry as new discoveries are found. Ideally, working with a welding glass producer to create an idealized combination of glass filer and light source, coupled with a hood manufacturer to mount the light in the welding hood itself, activated by the arc itself would create an even more interesting result. The next phase for me is to prototype such an animal for my own use. Stay tuned.

 

Plants are becoming big fans of LED light, thriving on the delivery of the light they need, without the waste of white light they don’t even see.

The use of LEDs in agricultural applications is expanding along side visual light and light cure technologies. The technology is even more compelling here for its reduction in energy consumption and lack of heat in the light pattern. The key element of LEDs in this application is the ability to create a specific spectral power profile, with none of the peripheral light unnecessary to get the job done. The light plants need is not the same as human vision. In fact, it is almost the opposite. While we humans with our juice camera eyeballs respond to light in the yellow-green spectrum to see by, our blind little green friends use light in the red and blue ends of the spectrum to activate various chemical reactions to generate food, build cells, and dispose of waste. (more…)

Overall height is 19". The base is a salvage item from Goowill.

Overall height is 19″. The base is a salvage item from Goodwill.

I am a task lighting fanatic. I use them everywhere, so am always looking for something new to add to my collection. In this installment, I am addressing the need for a light that is compact, delivers intense light (1,200+ Fc) with no glare or brightness, and high color accuracy. The application is pretty straightforward, from soldering station use where a magnifying glass is used, to fine detail work inside or on the outside of models.  For good measure, I also wanted it to aim at the wall as a photo fill light, or straight up as am ambient fill light, and have a dimmer to allow me to set whatever level I want for the application in hand at the moment.

The wiring and components are left skeletal.

The wiring and components are left skeletal.

With all the practical specifications set out, I decided to let this design be expressive of the gadgetry involved. Let it all hang out. I also decided to incorporate the new Bridgelux Vero LED with its integrated Molex connector, and a Nuventix cooler, just to amp up the tech factor.  This is where things got interesting. The Bridgelux array operates at 33.7V (500mA). The Nuventix cooler at 12V. I am powering the whole thing with a 24VDC wall wart power supply. That meant I needed to employ a boost driver for the LED and a buck (24VDC to 12VDC) power converter for the Nuventix cooler. I used Recom components to attain this, and used a cut up experimenters printed circuit board to connect these two to the power supply, the cooler, the LED and the dimmer control. That’s a lot of wires to find a path for, so I decided to leave them to roam free, let everyone see the components as well.

The lever on the left of the head is the on-off slide switch.

The lever on the left of the head is the on-off slide switch.

This is a style of design I personally enjoy, and have been doing since the 1980’s, where we made little 12V lamps with fiber optics, MR16s, halogen burners, or automotive headlamps, often suspended from structures made of building wire. In this case, the stand I found at a Goodwill. It was a table lamp, whose shade was gone, and socket was cracked. I liked the cast iron base and single post stand, so nabbed it for a dollar and tossed it in the pile with my other finds, waiting this moment to be put to service.

The wiring at the driver and power supply are exposed as well as the mess of wires leading into and out.

The wiring at the driver and power supply are exposed as well as the mess of wires leading into and out.

If you look at the head, the switch is a sliding action, on the left side of the head. Pull it forward to turn it on, push it back to shut it off. A hole in the side of the housing allows you to see the action inside. No, there is no reason for this, other than it seemed more appropriate than an off-shelf toggle or twist switch.

The light on the task surface is at 1,425 Fc, the LED is 3000K, 97CRI.

The head can pivot 180 degrees from down to straight up.

The head can pivot 180 degrees from down to straight up.

D2-img-4

D2 Front View

This weeks project is a concept model exploring an organic form of twisted and tapering ellipses. The height is 24″, and it measures roughly 3 1/2″ x 2 3/4″ at its base. The design is intentionally simple, utilizing a single LED strip concealed behind a valence to one edge. Total power at full brightness is 5 watts, and output is roughly 400 lumens total. The interior is covered with White Optic material to create a diffuse soft edged luminance from within. There is a simple stem dimmer control at the base circuited in series to the light strip, and a two position switch to the side providing full-on / off / dim settings. This model is powered by a wall-wart 24VDC power supply.

This was printed on a 3D printer, sanded smooth and painted matte white. In a production version casting the body in ceramic with a matte glaze would render a more finished end product. Low power LEDs don’t require much thermal management, can be circuited with on-board micro IC current control driver, creating a very simple to assemble and economic end product. Even in this plastic concept model form, the costs of the entire assembly were under $200, with the power supply.

D2-Img1

D2 3/4 View

D2 View 2

D2 View 2

D2 Back

D2 Back

D2 Top

D2 Top

D2 Base

D2 Base