I had an old Canon iP4000 inkjet printer that quit working.
Thinking that I might be able to scavange some stepper motors and other parts, I took it apart.
I was surprised to see that there were no steppers - just various regular DC permanent magnet motors and IR/photoresistor sensors to precisely move the paper and inkjet carriage.
There are transparent disks glued to the gears and sensors positioned to monitor the track on the disks.
The strange part is that the track appears to be consistently the same darkness instead of alternate light and dark segments.
So how can this setup work???