Monday, August 9, 2010

Thoughts on LED lighting

Few machine vision people will argue that LED lighting is the way to go. Longevity and stability make LED the most robust solution for the majority of applications, the exception being when you need great intensity, such as in web inspection. But even that is changing as LEDs get ever brighter.

One consequence of this evolution however is that thermal management is becoming more important. Let your LED light get too hot and it’s life could become as short as those halogen bulbs you’re trying to avoid using.

Obviously, machine vision users of LED lighting have a responsibility to limit the temperatures around their installations – don’t forget that camera hate heat too – but the manufacturers are also working on smarter lighting products. There’s a great overview of technology development in “LED Drivers Get Smart,” published in Design News June 22nd, 2010.

One issue that concerns me though is the way in which LED manufacturers will achieve this thermal control. The approaches discussed in the Design News piece seem to boil down to restricting the current and thus dimming the output. That’s all well and good in a domestic situation but it could play havoc with a vision system. And one problem we face is that our industry is not big enough to have any real clout with the LED makers.

So what do we do? I suggest two actions: watch out for such “smarts” being incorporated into your LED lights, and manage the temperature in the environment around your vision system so as to avoid getting into thermal issues in the first place.

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