if (document.images) 
      {  
          button01on = new Image(); button01on.src = "http://www.rikenvitamin.jp/flame/img/h_bt012.gif"; 
          button02on = new Image(); button02on.src = "http://www.rikenvitamin.jp/flame/img/h_bt022.gif"; 
          button03on = new Image(); button03on.src = "http://www.rikenvitamin.jp/flame/img/h_bt032.gif"; 
          button04on = new Image(); button04on.src = "http://www.rikenvitamin.jp/flame/img/h_bt042.gif"; 
          button05on = new Image(); button05on.src = "http://www.rikenvitamin.jp/flame/img/h_bt052.gif"; 
          button06on = new Image(); button06on.src = "http://www.rikenvitamin.jp/flame/img/h_bt062.gif"; 
          button07on = new Image(); button07on.src = "http://www.rikenvitamin.jp/flame/img/h_bt072.gif"; 

          button01off = new Image(); button01off.src = "http://www.rikenvitamin.jp/flame/img/h_bt01.gif"; 
          button02off = new Image(); button02off.src = "http://www.rikenvitamin.jp/flame/img/h_bt02.gif"; 
          button03off = new Image(); button03off.src = "http://www.rikenvitamin.jp/flame/img/h_bt03.gif"; 
          button04off = new Image(); button04off.src = "http://www.rikenvitamin.jp/flame/img/h_bt04.gif"; 
          button05off = new Image(); button05off.src = "http://www.rikenvitamin.jp/flame/img/h_bt05.gif"; 
          button06off = new Image(); button06off.src = "http://www.rikenvitamin.jp/flame/img/h_bt06.gif"; 
          button07off = new Image(); button07off.src = "http://www.rikenvitamin.jp/flame/img/h_bt07.gif"; 
        }
function imgOn(imgName) {
          if (document.images) {
                document[imgName].src = eval(imgName + "on.src");
          }
}
function imgOff(imgName) {
          if (document.images) {
                document[imgName].src = eval(imgName + "off.src");
        }
}