i=1;
function replay()
{
    i++;
    if(i>4){i=1;}
    var FileName= ( i < 2 ? "title_r_bg.gif" : "title_r_bg"+i+".gif");
    document.getElementById("title_r").style.background="url(/images/"+FileName+") right no-repeat";
}
    setInterval("replay()",6000);