Posts Tagged ‘Solid-state lighting’

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…)

Edit May1

As demonstrated in D1 of this series, LEDs and solid-state technology are changing more than general illumination. Other instances of applying near UV  LEDs with emission to cure light-cure resin composites. We have applied this to replace Metal Halide light sources that require 20 minutes to start-up, and are skin frying monsters. LED cure lights are also more predictable and focus-able than natural light, and can be applied indoors, and less bulky and more powerful than fragile fluorescent cure systems. LED sourced cure lights are now used in printing, dentistry, and commercial production of resin-based composites. We are also applying this on small and large scale applications from the very small (like D1 SLA curing) to larger scale units for curing large objects, like fiberglass repair of boat hulls, custom automotive body panels, and low odor repair of fiberglass bathtubs and shower floors. The use of LEDs produces instant-on high intense light, with much less power,  significantly less heat in the lighted pattern, less exposure to hot surfaces, and contain none of the damaging ultraviolet light that does nothing to enhance curing, but is harmful for operators. The use of UV initiated resins offer the advantage of extended shelf life as there is no catalyzed resin to harden in the container and less odor for use indoors. An update with  new images and details will be posted here when available.

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.

The 3D printed shade was an interesting experiment. Can also print in red or blue plastic.

The 3D printed shade was an interesting experiment. Can also print in red or blue plastic.

In playing with the Philips Hue system, we found wireless controls to be an effective means for solving lighting issues we have around the house. One area is the main stair. While the overhead track lighting system does a fair job lighting the art on the walls, it is a bit much when all we want to do is have a little light to navigate by. I also wanted to have the light turn on and off automatically, to provide a level of ease, and to get rid of the issue of forgetting to turn off the stair lighting on the way to bed.

The view from the floor below.

The view from the floor below.

Applying a wireless light, programmed to turn on-off and dim is a great addition, and an opportunity to create a new fixture while I was at it. The added feature of color changing to suit the lighting mode is a serious bonus and a lot of fun. Since the light from the stair itself is visible through a window facing the street, the effect of color here creates an interesting effect from outside as well. This design explores printing translucent materials for creating the shades, in addition to printing the rest of the fixture from ABS overall. The design itself is a bit freestyle, mixing a little Art Deco with Hi-Tech, influenced a little by American Indian… The light source is the Philips Hue A-style lamp, which has been modified through the addition of a bottom shade closure to hide the light source from below. The challenge with this design was to hide any direct view of the light itself, as at night the brightness was too great. I would like to have eliminated the cord connection, but tearing the stair railing apart to drill a wire channel through it was not on the agenda.

The 3D printing process (FDM) adds texture to the shade material.

The 3D printing process (FDM) adds texture to the shade material.

Now, we let the light run its program, and don’t have to remember to turn things off when retiring. We can also use the light to create a visual presence when we are out and away by setting different on-off times, color effects, etc… which from the outside, looks like things are moving and changing inside.

Deco-Tech is the best I can come up with to describe the design vocabulary used. It's really just freestyle.

Deco-Tech is the best I can come up with to describe the design vocabulary used. It’s really just freestyle.

Interesting note about color in this application. The very low blue light level makes seeing things in the stair when no other light is present very easy, so the level can be set low. Yet, this setting is easily ignored, and does not feel like a light on in the hall. I’m not concerned about the blue color interfering with sleep or melatonin suppression in this application, simply because the total energy we are talking about is so low (<.1 Fc).

Unfortunately, digital cameras have a hard time dealing with saturated colors, so this photo fails top show what this actually looks like (blue lighted portion). You can get the idea though, and having it cycle slowly through different shades is very pleasing.

Unfortunately, digital cameras have a hard time dealing with saturated colors, so this photo fails top show what this actually looks like (blue lighted portion). You can get the idea though, and having it cycle slowly through different shades is very pleasing.

warm

I was hoping to get a better image of this with the setting at 2200K and some saturated colors. Unfortunately the camera is fighting me, so I’ll just leave these with you to suggest how the fixture looks in other than white settings.

 

The Purple Light ‘UV’ Cure Cube

The Cure Cube is used for curing SLA 3D Prints created on the Form Labs 1+ printer. Exposing SLA prints to 405nm "UV" light increases strength and creates a harder surface for final finishing.

The Cure Cube is used for curing SLA 3D Prints created on the Form Labs 1+ printer. Exposing SLA prints to 405nm “UV” light increases strength and creates a harder surface for final finishing.

While not particularly visible to everyone in the SSL universe, over the past few years one area of interest in LED product development for me has been in use of 405nm LED light sources to cure various plastics materials. The advantages are lower power requirements and reduced overall heat in the cure zone over conventional fluorescent or HID light sources. This has been of particular interest in curing fiberglass resins manufactured by Sunrez. The typical demand is for between 200 and 1,000 µW/CM² at 400-405nm wavelength. The use of LEDs allows us to generate exactly that without the waste of visible light, and longer wavelength power the resins are not reacting to. In one project, we were able to replace a 1,500W HID light source with a 120W LED light system that produced faster cure times with less than 10% of the total power, and virtually no heat added to the heat generated by the resin’s exothermic reaction to the curing initiator. Since then, we’ve built 405nm light cure fixtures ranging from 1,200W to 25W.

In this case, I needed to cure 3D prints we generate on a Form Labs 1+ 3D SLA printer, and do so in an office environment without exposing other materials and occupants to UVA light output. The material used in the print process is acrylic based, with chemistry that is photo-reactive to 405nm. The actual prints are made using a UV laser source. When the part is removed from the printer it is washed in alcohol (91% IPA), rested for a few hours to dry the alcohol off, then placed in this cure cube for an hour or more, depending on the thickness of the final component. The end result is a hard first surface for finish sanding or painting, if necessary, and a more rigid part as a whole (less flexible).

The cube is simple, with vent reliefs top and bottom to encourage ariflow. The flush switch on the top cover was created using 3D printing processes for the slider and body, as well as top and bottom cover.

The cube is simple, with vent reliefs top and bottom to encourage ariflow. The flush switch on the top cover was created using 3D printing processes for the slider and body, as well as top and bottom cover.

The cube utilizes a simple aluminum housing, with FDM 3D printed top and bottom covers. The top cover houses a single Recom 500mA driver, slide switch and wiring terminal block on a Tasca LED driver circuit board.

5mm 450nm LEDs with a FWHM distribution of 60º, 25 per side and top (125 total), operating at 20mA each, mounted to custom circuit boards sourced at Express PCB. Each board connects the LEDs in parallel, while the boards are connected in series, resulting in a 500mA, 15.4V circuit, totaling 7.7W. The boards and internal exposed surfaces inside the box were then covered with White Optics 98 matte material to increase total light energy and diffuse The light energy at 405nm is roughly 600 µW/CM².

The bottom surface includes a glass plate where the product sits in order to make any possible stickiness of a part from adhering to the White Optic material below.

The interior of the cube is covered with White Optics 98 material for optimizing light energy re-cycling.

The interior of the cube is covered with White Optics 98 material for optimizing light energy re-cycling.

The housing was powder coated matte black polyester to make clean up easy and the box look nice. The overall interior dimensions of the box are 1″ larger than the total build volume capacity of the printer itself (5 x 5 x 6.5), as any over-sizing is unnecessary. This produces an optimal match between the location of the LED sources and any part the printer can produce.

The Cube is powered by a remote plug mounted 24VDC power converter.

The operation of the box is simple enough. The box is lifted up, the part is set on the base, the box is set over the part, and the light is turned on by sliding the switch to the on position.

Simple and compact is the order of desktop manufacturing, and this fits that model perfectly.

A look into the box lighted up and ready to accept parts.

A look into the box lighted up and ready to accept parts.

Testing so far has shown the cube can cure raw resin from liquid to fully hardened in less than an hour, and strengthens prints in that time or less. The heat generated from this arrangement is so small, there is no chance of any part being warped or affected by the process, other than the desired results of becoming stronger.

For parts to be left unfinished, that are desired to be used over extended periods, we coat the finished parts in either acrylic or polyurethane UV inhibiting clear coat, gloss or matte. This stops ambient room light or daylight exposure from making the parts brittle over time. I am building a second copy of this cube for completing extended testing of samples of the materials we are using to verify clear coat effectiveness, behavior of the print material over long exposure periods, and the behavior of these low cost LEDs over time. A commercial version of this cube could be made using more robust LEDs, but the costs would be significantly higher as well. In the current configuration, the LEDs only cost $0.60 each, so should they last a couple of years in use, replacement of the populated boards is a simple task, while the cost of higher power LEDs would have increased the cost of the entire end-product by as much as three times.

There is also an additional version of this same approach in using Red/Blue light sources for use in plant seedling starts. We’ve found tests with common rye and barley grasses, the time from germination to hearty growth ready for planting is accelerated significantly. Using an enclosure like this allows the plants to be exposed to intense light for extended periods of time (18 hours or more) without polluting the surrounding environment with the ugly light, just as the enclosed cube protects room occupants from exposure the the UVA light. In either case, the cube can be used in any room environment comfortably and safely.

So this gets us off the ground and is D1 of 52 in the series. As I’ve noted at the start, this is an exercise in making progress, and putting SSL to work. This is not a particularly exciting product in and of itself, but it is one that will be used regularly, which more than makes up for its lack of marketing sizzle for the masses – at least in my book.

 

2015 is the International Year of Light and Light-based Technologies – a United Nations observance to raise awareness of the achievements of light science and its applications, and its importance to humankind. 

Edited 12/10/2015:

The concept of pursuing another round of 52 designs in 52 weeks was the original intent for this series. However, the time involved was not available, nor were we able to rationalize the costs involved. The work of the 52/52 2010 was a significant effort, that never truly delivered an ROI, either directly or indirectly. It was a lot of fun and reflected my exploration of SSL technology on a fast track. I’d hoped to attract others in playing along this time around. This never materialized. Faced with going it solo again, I came to the realization I just couldn’t get it done, so abandoned the project. It is a serious disapointment, but did free me the time to refocus on our business and move us into a larger and more productive state and facility, so not all was lost. The original 52/52 designation for the projects has been re-titled YOL, for the Year of Light. Yes, it is a bit of revisionist history, but its my blog and I have that right.. literally and figuratively.

With that in mind, I am still sharing projects being worked on within Lumenique that are exploratory, experimental, or customer project related (when we are allowed).

In 2010, we explored everything from steam punk to toys and practical tools. 2015 will be more of the same with a 3D twist.

In 2010, we explored everything from steam punk to toys and practical tools. 2015 will be more of the same with a 3D twist.

I combine work with solid-state light sources with another emerging and revolutionary technology we started working with in 2010 – 3D printing technologies. I now have (3) such printers on hand, including a commercial FDM printer, a desktop FFM printer, and a desktop SLA printer. With these, we can now make translucent and transparent prints, including simple optics, flexible parts, and smaller, highly detailed components and mold patterns for casting in metal and urethane. I’m anxious to put these to work in creating interesting final forms. I’ll also be firing up the glass kiln a few times, and hammering out a few pieces in the blacksmith shop to keep things interesting.

In the next few days, I will be posting my first entry to start the ball rolling with something for my shop, that others in the 3D print business may find useful.

That all said, I hope that 2015 has been a great year for everyone!

 

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 participation 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…)