Optical Mouse-How it works+what are these components

[pat666]

Homework Statement

Pictures of an optical mouse I took apart are attached. We had to find a circuit, take a picture, draw the circuit diagram and explain how it works.

I'm not sure what a few of the components are. U3 is for the scroll wheel but what is it? U1 (the big IC) is the guts of the circuit but when I google B0863C (number written on it) I can't even get a data sheet for it. I know it registers something to do with the light reflected back into it but what? does the wavelength change when I move the mouse or something? Also is the light source just a standard LED or is it special? Also there doesn't seem to be a U2 where would that be? And what is U standing for in general (R is resistor, C is capacitor etc) .

Finally, what is Y1 - it looks like a capacitor and is right beside the IC.

Thanks for any help

 

[lewando]

It is probably something similar to the Avago Technologies ADNS-7050.
Datasheet: http://www.avagotech.com/docs/AV02-1411EN"

"U" is the letter used for IC reference designators.

"Y" is used for crystal, oscillator, or resonator