function randNum() 
{ 
    randNum.today=new Date(); 
    randNum.seed=randNum.today.getTime();
　　randNum.seed = (randNum.seed*9131+59297) % 432680; 
　　　　return randNum.seed/(432680.0); 
}
function rand(number) 
{ 
　return Math.ceil(randNum()*number); 
}
function ChangeCodeImg()
{
      var a = document.getElementById("ImageCheck");
      a.src = "../ctrl/CodeImg.aspx?"+rand(1020000);
           //  document.all.ctl00$ContentPlaceHolder1$Btnsend.disabled = true;
} 

function ChangeCode()
{
      var a = document.getElementById("ImageCheck");
      a.src = "ctrl/CodeImg.aspx?"+rand(1020000);
           //  document.all.ctl00$ContentPlaceHolder1$Btnsend.disabled = true;
} 
// ChangeCodeImg();