function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		nav_main_on1 = newImage("../image/navi_main/1on.gif");
		nav_main_on2 = newImage("../image/navi_main/2on.gif");
		nav_main_on3 = newImage("../image/navi_main/3on.gif");
		nav_main_on4 = newImage("../image/navi_main/4on.gif");
		nav_main_on5 = newImage("../image/navi_main/5on.gif");
		nav_main_on6 = newImage("../image/navi_main/6on.gif");
		nav_main_on7 = newImage("../image/navi_main/7on.gif");

		nav_sub1_on1 = newImage("../image/navi_main/s4-1on.gif");
		nav_sub1_on2 = newImage("../image/navi_main/s4-2on.gif");
		nav_sub1_on3 = newImage("../image/navi_main/s4-3on.gif");
		nav_sub1_on4 = newImage("../image/navi_main/s4-4on.gif");
		nav_sub1_on5 = newImage("../image/navi_main/s4-5on.gif");
		nav_sub1_on6 = newImage("../image/navi_main/s4-6on.gif");
		
		nav_button_on1 = newImage("../image/call_back_on.gif");
		nav_button_on2 = newImage("../image/contact_form_on.gif");
		
		preloadFlag = true;
	}
}