LDR or optical reflective sensor? Answered

I am planing to make a line following robot without micro controllers.
So I am using a light sensor connected to an AND GATE (the other input being the current to the motor).
So since I am using" an and "gate I want the input current to be an absolute zero or some value ,ie the current should not be varrying with the light intensity.

Besides I think I might drop the "and gate" thing and use an OPAMP instead as it would give me a varrying output current which is all I need