//window.onload = function () {
//  chgBanner();
//};

//カウントUPフラグ
var cnt_up = new Array(banners.length - 1);

function chgBanner() {
  var buff = "";
  var rep = new Array(banners.length - 1);

  var max;
  if((banners.length-1)  < 4){ max = banners.length-1; }
  else { max = 4; }

  for (var i = 0; i <= max; i++) {
    var num = Math.floor(Math.random() * banners.length);
    if (rep[num] == 1) {
      i--;
    }else {
      var img_url = "";
	  if(cnt_up[num] == 1){ img_url = banners[num]["src"]+"&cntoff=1" }
      else { img_url = banners[num]["src"]; }

		if(banners[num]["url"] != ""){
      buff += "<a href=\"" + banners[num]["url"] + "\" target=\"_blank\"><img src=\"" + img_url + "\" border=\"0\" alt=\""+ banners[num]["alt"] +"\" vspace=\"2\"></a><br>\n";
		}else{
      buff += "<img src=\"" + img_url + "\" border=\"0\" alt=\""+ banners[num]["alt"] +"\"  vspace=\"2\"><br>\n";
		}

      rep[num] = 1;
	  cnt_up[num] = 1;
    }
  }
  document.getElementById("banners").innerHTML = buff;

  setTimeout("chgBanner()", 30000);
}