var imgArray = new Array();

imgArray[0] = new Image();
imgArray[0].src = "img/head/_1.jpg";
imgArray[1] = new Image();
imgArray[1].src = "img/head/_2.jpg";
imgArray[2] = new Image();
imgArray[2].src = "img/head/_3.jpg";
imgArray[3] = new Image();
imgArray[3].src = "img/head/_4.jpg";
    
var i=-1; 

function changeImages()
{
	i++;
	
    window.document.images[2].src=imgArray[i].src;

	if (i==3)
	{
		i=-1;
	}

	window.setTimeout ('changeImages()', 3000);
}