var secs = 1;
function Load(){ 
	for(var i=secs;i<=4;i++) { 
	  window.setTimeout('doUpdate(' + i + ')', (i-secs) * 4000);
	}
}
function doUpdate(num) { 
	for (var i = 1;i<=4;i++) {
		document.getElementById("bt"+i).className = "";
		document.getElementById("i_banner_"+i).style.display = "none";
	}
	document.getElementById("bt"+num).className = "current";
	document.getElementById("i_banner_"+num).style.display = "block";
	if (num == 4) {
		window.setTimeout('Load()', 4000);
	}
}
window.onload = function() {
	//MM_preloadImages('${path }/szsx/images/index_img/service_onpic4.jpg');
	Load();
}
function showBanner(num) {
	for (var i = 1;i<=4;i++) {
		document.getElementById("bt"+i).className = "";
		document.getElementById("i_banner_"+i).style.display = "none";
	}
	document.getElementById("bt"+num).className = "current";
	document.getElementById("i_banner_"+num).style.display = "block";
}