The Efficiency Thing – Why an Artist Would Care

LEDs bring a lot of creative potential to the lighting market. At this creative front will be artists who apply them in unique ways outside the mainstream general illumination marketplace. I’m one of them in fact. Gone are my days of fooling with halogen lamps and transformers – now its LEDs, drivers and power supplies… and heat sinks.

The first wall hit in application of LEDs is their output and thermal dynamic. In halogen lighting, the fixtures got hot, no big deal. As long as it wasn’t peeling flesh or raising a blister, its was fine. LEDs don’t work that way. Long before the lighting portion gets hot enough to raise a blister, the LED is fried, game over.

Ultimately, the goal of an artist in creating a new work of light is to generate as much light as possible in the smallest, most innocuous package. That makes LEDs at once attractive, and a problem. To illustrate, a 350mA 1W LED requires very little thermal management to survive. Glue or screw it to plate of aluminum or copper and its happy. Problem is, the amount of light is pretty weak, between 35 and 60 lumens if you want 3,000k color with good color rendering (yes, artists do care about color – a lot.) That’s a long way from the 600 to 800 lumens we were used to in halogen sources. Optimally, for a task light with a good optic (wide smooth beam), gettting to around 350 to 500 lumens is optimal. This means more energy. At 700mA, 100 lumens is attainable, and lands us in the 3 to 4 watt range. Three is always better than 10, so this sounds like the way to go. Problem is, a 3W LED is exponentially more demanding thermally than that 1W device. These higher energy devices demand heat sinks, real life thermal management, with airflow and everything.

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My First LED Task Light Sculpture – Vintage 2005

This is my very first functional LED task light, completed at the end of 2005. Construction is welded steel. Originally, the main components of this fixture (2004) were designed for a 12V/20W Halogen bi-pin lamp that created an overheating of the lighting head and poor light output. This was changed to (12) 1/2W Nichia HB LEDs (2800k) mounted to PC board with through hole thermal connection to the heat sink, as an experiment and proof of concept for the application of LEDs to provide greater light output for the same or less energy. Light on the task surface was either 70FC or 150FC, with a very wide distribution, as there is no secondary optical control. An aluminum heat sink inside the lighting head maintains reasonable operating conditions for the LEDs (under 60C TJ), while remaining cool to the touch. The horizontal arm ratchets up and down, the red arches are fiberglass springs that tension the ratchet. The parallel link on the head and arm keep the head level when it is adjusted up and down.

This “Ratchet” fixture was my first attempt at an LED sculpture design.
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