Hello Everyone!

I'm doing a reaserch paper on webcam image sensors.
I'm trying to find out whether there are few main image sensors manufacturers who supply to all the webcam companies or whether each camera has a different sensor. my question is simply if Logitech, Creative, Hp etc all use the same sensor (and if yes then who is it) or they all use different sensors.
In addition, all webcams have an image processing chip (beofre the pic/frame enters the computer). where can i find what kind of processing does a certain camera has? are all image processing chips similar? manufactured in the same fabs?

I tried to find info on the web but with no luck
please help
thanks