Using proximity sensors to sense bottle caps

I have had very good results with Keyence laser sensors. The GV series is their top of the line but are a little pricey: $700 for the amplifier and sensor head. They have so many features built into the amplifier its unreal. These have an adjustable response time of up to 1.5 ms and also have a detection deviation of up to 1/2 mm. So you could set a sensitivity window up just to sense the cap, not the edge of the box. Off delay is also available if you need it. (Not sure of your belt speed or scan times). The LR-ZB series is not nearly as fancy but is more reasonable ($300). And its self contained (no seperate amplifier) Same response time of 1.5ms but a detection deviation of 9mm if you can be within 180mm of the cap. It doesn't have the window function so you would need a sensor just downstream to tell that the box had cleared. It does have the off and on delays. This also assumes the boxes are coming down the line in the same place. If not, you can angle them to catch the neck of the bottle. You can go to Keyence.com for more info.

I just re-read my post and I sound like a salesman. :angr: