/* 画像の先行読み込み */
if(document.images) {
 var imgs = new Array();
 imgs[0] = new Image();  imgs[0].src = "image/mn_home_on.gif"; //画像パスを入力
 imgs[1] = new Image();  imgs[1].src = "image/mn_product_on.gif";
 imgs[2] = new Image();  imgs[2].src = "image/mn_download_on.gif";
 imgs[3] = new Image();  imgs[3].src = "image/mn_gallery_on.gif";
 imgs[4] = new Image();  imgs[4].src = "image/mn_case_on.gif";
 imgs[5] = new Image();  imgs[5].src = "image/mn_store_on.gif";

 imgs[10] = new Image();  imgs[10].src = "image/mn_home.gif"; //画像パスを入力
 imgs[11] = new Image();  imgs[11].src = "image/mn_product.gif";
 imgs[12] = new Image();  imgs[12].src = "image/mn_download.gif";
 imgs[13] = new Image();  imgs[13].src = "image/mn_gallery.gif";
 imgs[14] = new Image();  imgs[14].src = "image/mn_case.gif";
 imgs[15] = new Image();  imgs[15].src = "image/mn_store.gif";
}

function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}