function move() {
	if ( i < step) {
		tmp = tmp * k;
		window.scroll(0, start + (difference - tmp));
		setTimeout("move()", 0);
		i++;
	} else {
		window.scroll(0, difference + start)
	}
}
	
function getWinYOffset(){
	if (window.scrollY) return window.scrollY; // Mozilla
	if (window.pageYOffset) return window.pageYOffset; // Opera, NN4
	if (document.documentElement && document.documentElement.scrollTop) { // 以下 IE
		return document.documentElement.scrollTop;
	} else if (document.body && document.body.scrollTop) {
		return document.body.scrollTop;
	}
	return 0;
}

$(document).ready(function() {
	//IE6で透過PNGを使用可能に
	$(".alphaFilter").pngfix();
	$("a.f_img_tophe").click(function(){
		step = 50;
		point = 0;
		start = getWinYOffset();
		difference = point - start;
		tmp = difference;
		k = 0.90;
		i = 0;
		move();
	});
});