Monday, June 28, 2010

In praise of high frame rates

I see and hear lots about the value of high sensor resolution, but almost nothing about what high frame rates can do. I think that represents a missed opportunity.

The benefit of acquiring many images, when you’re performing part inspection, is that it provides, as the TV people say, “another chance to see.” Let me explain: imagine a situation where a part moves under a camera. The camera receives a trigger and acquires an image. There’ll be some slight positional variation image to image due to the inherent variation in the system (jitter and so on.) Odds are, this variation also means the lighting varies subtly from image to image.

Usually lighting variation is the enemy, but I’d argue that by capturing multiple images it can be your friend. Say you’re trying to read a pin stamped code on a moving part. Rather than grab a single image and hope for a good read, grab several images and see which one gives the best read.

This is why I’m a fan of the Cognex Checker. Yes, the resolution is low, but the frame rates are very high, so with a little imagination this sensor can be used to perform some quite interesting inspection tasks.

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