After two postings about LED lighting and working on more, I have decided I didn’t like the way the series was developing. It was too much cart before the horse. I want these posts to be useful for everyone and I felt the LED discussion was getting too technical without explaining why any of it mattered. Therefore, I am going to start over with a new introduction to LED lighting.
LED lighting is a game changer, but not in the way most people discuss it. It is not because of the efficiency or size or whatever, but because it is so fundamentally different from the way we have created light for ourselves. This may or may not be the future of lighting. It seems to be direction everyone is traveling at the moment, but that doesn’t mean we won’t find another alternative before we fully adopt, and adapt to, LED lighting.
There are two main reasons LED lighting is such a huge change. This post will focus of the first of the two, which is that LED lighting is an electronic, rather than electric, approach.
Imagine for a moment you are back in the early days of electric lighting. Up until this time, light was generated by burning a fuel at the point where you wanted the light to be. You might have a whale-oil lantern or a wax candle, but in any case the location of the light had to have both a supply of fuel to be consumed and a flame. At some point, your fuel would be used up and you would need more.
Then this new technology arrives that promises to change everything. By using an electric light you separate the fuel from the light source. Previously, if you knocked over an oil lamp you had to worry about a fire breaking out. Now, if you break an electric light bulb it just goes out. You no longer had an open flame at every light source. Now, each incandescing filament is surrounded by a glass envelope. Granted, there were still plenty of fires started by bad wiring or things touching a hot lamp, but it was a safer than having flames and combustible materials everywhere. You could wake up at night and press a switch to turn on the light instead of fumbling around in the dark for your taper.
The electricity became the new version of the fuel. How much electricity you got determined how much work was done by your motor or light bulb. You could plug in a light bulb and if you kept giving it more electricity it would get brighter and brighter until it broke. Electricity was “power,” and the power means getting work done.
All of our lighting advances since then have gone along the same lines: electricity means power. Various circuits have been designed to take advantage of that power in different ways, and different lamps take advantage of those circuits in different ways, but it is still essentially using electricity to power a light source, and creating that light is the work we want done.
LED lighting is different because electronics are different than electrics. Electronics use electricity as the power source, but they also use electricity as the information source. I’ll use digital electronics as the example since analog electronics are a confusing middle ground.
In a digital circuit the idea is to use the current as the information. Imagine you want a digital light switch. The entire device will need two circuits: one circuit to figure out if it is supposed to be off or on, and a second to actually power the light. The two circuits can’t be shared, because if they were the result would be something like: “if the light is on, turn the light on, and if the light is off, turn it off.” That wouldn’t actually do anything useful. Instead, we have one circuit which is “smart.” It knows that if the current flows in a particular direction at a particular power, it is supposed to be “on.” If the current doesn’t meet those requirements, it is “off.” If the control circuit is “on,” it tells the work circuit to flow, turning on the light.
The point here is that diodes, like an LED, were and are designed to function as a part of the control circuit, not the work circuit. To make LED lighting work we have to design a control circuit act as a work circuit. That’s the point of including the stuff about circuit boards and drivers in my previous posts. Power is supplied from the power company in the work circuit form, which then has to be converted to a control circuit form to let the LED function. However, the LED has to function as a work circuit, and the only way that can be accomplished is by proper fixture design. That’s why we can’t just stick a bunch of LED modules on a wall and expect an efficient and effective lighting system.
Tags: LED lighting
