var scan = new Array();
 scan[0] = new Image(); scan[0].src = "image/scanner_dea.png";
 scan[1] = new Image(); scan[1].src = "image/scanner_akt.png";

 var i = 0;

function bildwechsel_scan() {
  if(i > 1) i = 0;
  document.getElementById("scanner").src = scan[i].src;
  i++;
  window.setTimeout("bildwechsel_scan()",1000);
}