Accessing this in anonymous function

Accessing this in anonymous function

I want to create a prototype function that has its own scope. For this, I
use an anonymous function but I cannot find a way to access the members of
the object.
Here is a simplified version of what I am trying to achieve:
function F() {
this.counter = 0;
}
F.prototype.increment = (function() {
var lastIncrementTime = -1;
var caller = this; // <--- it fails here because this is the Window
object
return function(time) {
if (time > lastIncrementTime) {
caller.counter++;
lastIncrementTime = time;
return caller.counter;
}
return caller.counter;
}
})();
f = new F();
f.increment();
I know it fails because this does not refer to F or the f object.
Is there a way to access it?