Best sensor to detect BLACK object

Hi;


We need to install a sensor to see the running web (sometime brown web sometime white) of a corrugator machine whose max speed is 250M/min. When an A4 sized BLACK paper is detected on that running corrugated web, sensor should give a pulse to system. Goal is to detect the BLACK A4 Paper on running web. The min distance of sensor to web will be 400mm i.e. we can not move the sensor more down. System voltage is 24VDC.



Do you please guide me which kind/brand of sensor is the best to use for such application? The viscosity of ink on said A4 sized black paper is changed i.e. sometime pure black and sometime light.



We have tried regular defuse type sensor but sometime it works sometime not. We need 100% results.

SWAG


I would contact SICK with your application. Is there a UV property to the material? I've used that in the past for detection.


HTH

You could have a look at the Keyence LR-W500 full spectrum sensor? 30-500 mm range. I've used a couple to good effect...

https://www.keyence.com/products/sensor/photoelectric/lr-w/models/

Regards,
George

If no sensor can adequately sense black material I would put a sensor that doesn't respond to black and either a through beam, ultrasonic or sensor/reflector that will detect any material.

If the through beam/reflector/ultrasonic says there is material but the other sensor is Off then it must be black and not visible.

+1 Aabeck
https://www.automationdirect.com/adc/overview/catalog/sensors_-z-_encoders/color_sensors/3_color_sensor

https://cdn.automationdirect.com/static/manuals/lasersensorsmanual/opt2023.pdf

The above sensor will allow you to teach different colours with tolerance.
These would have to be tried in order to determine the suitability.

Regards,

I've also had good luck with a Keyence colors sensor years ago in a food packaging application.

Depending on the sheen of the black material no optical sensor may see it ever. If it is similar to flat or satin paint sheen it would not be seen at all. If it is gloss or semi-gloss then a perpendicular sensor could reflect off the sheen and not necessarily be able to sense the actual color.

Sick do colour sensors that work quite well, used these on detecting a black ink splodge on soap packets for rejects, however, we also had a second sensor to detect the pack as the black mark was the same as no product but this should not apply in your case. To be honest, most sensor manufacturers have colour sensors but these are not cheap, I suggest if you have contacts with reps from sensor suppliers you get them in and do a trial if you can.

Have you considered a retroreflector type sensor - assuming all objects are opaque.

We generally use contrast sensors, but if brown AND white are acceptable and black isn't that's going to be tricky.
I might just use a color vision camera instead.

I used to be in the web offset printing business with 4 colors.
we used a black tick mark for the folder cut signal.


please explain your application a little better, what is going on at the sensor location?


james

Teachable ultrasound sensors would work.
Run the black into the sensors range and use the teach function.