Light "Progress"

Light "Progress"

There is something that has bothered me for quite some time, so this time I do write something related to my current work. In case you think this is too long here, I also put it onto my (finally revived) site:
http://dl7und.net/eng/Articles/Light-Progress

How would you like if your car looked like a horse-drawn carriage? It would still have stereo, power windows and all, because that is current technology, but would look like a carriage, a bit like the first automobiles. There would however be one difference: While those early automobiles were called so because they had an engine on board, your “car” will not.

Instead there will be two horses pulling it. Oh, not real horses of course, because we don't use horses anymore, that is a bit outdated, yesterday's technology. No, those are mechanical skeletons, shaped like horses, sometimes even wrapped up to look exactly like horses, each with a small V6 engine inside. Engineers have spent lots of efforts to transform the rotation of the engine into natural and smooth leg movements, so it looks quite like real horses are pulling your car.

Not later than at this point you are probably calling me crazy, and rightly so. Who in their right mind would do this? Nobody, as far as I can tell. But who in their right mind would do something like this? Almost a whole industry, as it appears.

You may have noticed how the use of LED is all the rage now in lighting, has been so for a few years now. You may also have heard the term “retrofit” in that context. It basically means replacing an old light source employing old technology with a new light source employing new technology, the new light source being equivalent to all relevant specifications of the old light source. But have you ever considered what that means in reality?

The bulb type most advertised is probably the so-called “Edison bulb” (No, he didn't invent it.), also called “globe bulb”, or “A-type bulb”. The current trend is even to offer “omnidirectional” bulbs, meaning bulbs emitting light in (almost) all directions. Basically, they are LED bulbs that are supposed to look and behave just like the incandescent bulbs that were designed more than a hundred years ago. Do you hear a horse whinny?

Jubal Early would have loved the incandescent bulb, had they still existed in his time, because they adhere to his beloved design rule of form following function. “Function” here does not just mean what a device does, but also how. While it is highly inefficient as a light source, the incandescent bulb is a beautifully meaningful design.

We have a piece of wire that is heated up by the current flowing through it, to a degree that it not only gets warm, but starts to glow, up to emitting a hot white light. It would burn up within a moment if it was exposed to air then, so we better enclose it. We still want to see the light it emits, so it must be an enclosure that is airtight, transparent/translucent and heat-resistive. Glass is the obvious choice. And to get as much light as possible, we will elevate the wire a bit from the point where we have to use non-transparent material (the socket) to provide electricity.

There is however a small disadvantage with such a bulb: While it emits light in nearly all directions, we do not always need that. When we install a bulb at the ceiling, we usually need light down here, not at the ceiling. I am not a spider who could walk up to the ceiling, so my plate is down here on the table, as is my book. Here I want light. So mankind invented light shades that block or reduce light in some directions, while reflecting it in others.

Enter LED, stage left. A LED is a semiconductor, which means it does not like heat. It performs best at rather low temperatures, like in your fridge. When it gets hot - and that is bound to happen during operation – its performance degrades. So we need to get the heat away from a LED, something we didn't have to worry about with incandescent bulbs – at least the bulb itself was not affected by the heat it emitted.

LEDs also emit light only at an angle of less than 180 degrees, even with the help of a lens. This sounds like a great solution to our problem with blocking and reflecting incandescent light, right? Finally we could create light sources that do not need a shade/reflector, light sources that emit light in the direction we want.
Add to this that (high-power) LEDs generate heat, but that they do not like it, and the logical conclusion should be area or line light fixtures with enough distance between two LEDs to allow for unproblematic convection cooling, without having the LEDs affect each other. For most companies, this is just theory.

In reality, huge armies of engineers are trying to cram LEDs into the small space offered by a globe bulb, nearly going mad because they need to come up with new ideas to get rid of all the heat generated. No matter how good they are, in the end they still need to issue the usual disclaimer, which was not necessary with incandescent bulbs: Do not operate our product within enclosed or badly ventilated tight spaces, or it will overheat and die.

Crazy, is it not? We are trying to imitate a design that was made for a technology more than a hundred years old, with new technology that could easily avoid the shortcomings of said old technology, and by imitating we create problems we wouldn't have faced had we not tried to imitate. You may think it is hard to top this, but that has already happened.

Let's get back to the term “omnidirectional”. This is the latest “trend” in globe bulbs. It means that light is emitted in (nearly) all directions, just like the incandescent bulb did - the bulb which we put into a shade/reflector because we did not really need a lot of light at the ceiling. There are now even standards for how well a LED globe bulb imitates an incandescent bulb. And poor engineers have to come up with solutions as to how a bulb can be made to emit light at a 270 degree angle with semiconductor components that only emit light at less than 180 degrees.

The resulting globe bulb can then finally be put into the same shades/reflectors as the old incandescent bulbs, and a large part of the light that was guided towards the bulb socket through a lot of engineering ingenuity is then redirected by the light fixture in the opposite direction. Please remember that one of the features always advertised with LED products is energy efficiency. I do however fail to notice how reflecting and redirecting light several times instead of sending it in that direction right from the beginning can be more efficient.

Yes, this is one of my pet peeves. But please do not think that now all those engineers must be absolute idiots. They are not. You can tell from the solutions they have to come up with. In fact, I suppose quite a few of them have the same thoughts I have. But unfortunately they have to come up with such solutions, because “the market” (That would be you and me.) demands them. Of course, “the market” demands them because consumers have been promised such solutions by marketing departments.

Not all companies are going this way, but if you look around, you will see plenty of organisations with masochistic behaviour. And there is more to the LED globe bulb than just design issues, there is also an economic angle. But that is a different story.
#ledlighting  
http://dl7und.net/eng/Articles/Light-Progress