function preloadimg(){
	preloadimg = new Array();
	for(i = 1; i < 6; i++){
		preloadimg[i] = new Image();
		preloadimg[i].src =  "common/img/tnavi_btn"+i+"_on.gif";
	}
}


function chimg(filename,target){
	document.images[target].src = filename;
}