When "Labels reflect more light" that's nice you pointing that out, then I could have a sensor only on one side, that transmit and receive, and when there is a drop in the light, that is being reflected, I know that's a gap between labels, ->one label
the speed is not important, the bigger the roll is getting, the faster the speed, so I was thinking about using a electric motor, that have fixed RPM.
I will put a electric motor, that's rotate on the side there is pulling, but I need some sort of resistance, on the other side, so the tape will be stretched.
will a QRE1113 Line Sensor do the job, or QRD1114 Optical Detector / Phototransistor https://www.sparkfun.com/products/9454https://www.sparkfun.com/products/246
or is there a better solution ??
I don't know alot about sensors, and the specs, on the sensors says nothing about refresh rate ??