Question About Vision System Lighting

[TonysControls]

Quick background info: I am doing a project with a cognex IS2000 model camera with a 6mm lens and am using 80/20 for the frame of the camera. The goal is to do some error proofing for a process we have assembling manifolds (3in x 6in). I know the camera has a torch but personally have had issues with on camera lighting not being quite consistent enough for changes in ambient light.

I am getting a materials list together and was wondering if anyone had any advice for what kind of LEDs to use in a vision application like this. First time sourcing lights and just looking for what vendors/sites I should be looking at if anyone has any suggestions.

Thank you

 

[dploof23]

Not sure where you get your Cognex cameras from, but the company I get them from has a vision lab that provides testing to source the proper light/lens for the application.
Might be worth looking into.

Dave

 

[Robobob]

You mentioned changes in ambient light. My advice here in build an enclosure that completely surrounds the inspection area as much as possible. The less outside light that gets in the better. I cannot tell you how many times I have had to fight outside light sources in camera projects. Windows, changing shadows ect ect.

 

[drforsythe]

Amen to Robobob's comments! We have almost always ended up adding enclosures, roofs or other light blocking devices to keep lighting consistent. I also agree with dploof23's comment on using the value-added services of your camera vendor. All of the sources we have used in the past would do some validation. Depending on the application, you may choose to use infrared lighting. If IR works in your application, then you just have to guard against sunlight. We found greater consistency when we used IR lighting and a matching filter.

 

[Jim3846]

if it's an auto plant, there is a possibility that welding would interfere with your area, so maybe like above has suggested some opaque guarding of the light sources in area. If there is not alot of blowing wind in your area, maybe get away with velcro. Or if not then something that can easily be accessed by removing if needed.

I thought cognex had background teach modes for lighting if what you buy is a problem.

Cognex support is ok over phone or maybe find a local distributor of the product for support?

 

[L33er]

4 not-so-practical responses and none could come up with one good vendor, lol.

 

[SD_Scott]

Can you change the shutter speed of the camera? Not familiar with that camera. In photography, if I'm shooting in a studio with flash strobes and I set the shutter speed to 1/60 second, it will let some ambient light in. If I increase the shutter speed to 1/160 there will be less ambient light and mostly strobe light.

 

[tdoa]

Mostly from Stemmer Imaging, and some from Banner, but I'm in the EU..

But its kinda important to have someone validate your camera and lighting setup before committing to the final order.

Its also important to test various colors of illumination and if you need a planar, linear, dome, direct or indirect lighting, plus various filters.

If its a reflective part usually infra-red gives you better results, less reflections and a lot more immunity from ambient lighting.

Its not just a matter of trowing more light into the problem, 99% of a vision project is finding the correct illumination to properly differentiate what you want to inspect from the background.

 

[Picklemon]

I have used Smart Vision Lights for a long time:
https://smartvisionlights.com/

They have a lot of good information and videos on their site and they offer application support.

 

[dploof23]

4 not-so-practical responses and none could come up with one good vendor, lol.

Thanks L33er, that is also helpful....smh

The vendor I use is excellent, but Cognex has regional distribution so my vendor in MA will not be the same vendor the OP will use in his area.

 

[L33er]

I have used Smart Vision Lights for a long time:
https://smartvisionlights.com/

They have a lot of good information and videos on their site and they offer application support.

+1, that's what I had in mind last nite, LOL.

 

[KingBennon]

Does the flatness of the material being checked change?
Is this why your not getting a good image?
Is the part on a station?

If im checking a part that's on a lifter and flatness changes I use a CCS ring light as there cheap.

Everything else I use a flatlight.
Get as much light as you can on it.
Use a white light if possible.

 

[TurpoUrpo]

In my experience with vision, it is really important to control the lightning properly for the application. With really simple stuff, what ever comes from around might be enough, but the second you need something accurate -> enclosure with own lights AND control the angles!.

 

[KingBennon]

Normally I wouldn't really worry about ambient light.
We have a lot of LED over head lights that are not really an issue.
Just has long as the light is white and very bright, you don't really have to worry about it.
Most issues I find with lights are smartvision.
People use a 5 pin cable with 4 poles.
But smartvision requires 5 pole.
If you don't then light output will be 20% output.

 

[James Mcquade]

camera salesmen always promise to take your sample parts back to their lab and get it working, and they do. PERFECT ENVIRONMENT ! we live in reality.
All cameras are subject to plant lighting as well as outside lighting, forklift lights, signal beacons.
what works today when its cloudy is totally different on a bright sunny day. when plant lights are new, they are brighter, they get dirty, burn out, flicker when there is power issues and when they are about to burn out. also beware of salesmans promises, ask about the pixel size of the camera and how small of an area it will detect. also ask how they came up with the number.
you mentioned that the camera has a torch. how will you keep the camera lens clean due to carbon buildup, weld sparks, and the like. you also have to keep the camera at a relatively constant temperature, they have heat limits and the lens does change some due to heat expansion. as mentioned earlier, a protective hood is needed. but you also need to consider these items i talked about and the possible consequences.
james