var speed = 20;
var delayspeed  = 10;
var timerID;
var scry;
function scrollup(ysize){
timerID = setInterval('scrolls()', speed);
scry = ysize;
}
function scrolls(){
if(scry > 0){
scry = scry - Math.floor(scry / delayspeed ) -1;
parent.scroll(1,scry);
}else{
clearInterval(timerID) 
parent.scroll(0,0);
}
}