var winImprimir;

function imprimir(url){

	if(winImprimir && !winImprimir.closed){
		winImprimir.close();
	}

		w = 650;
		h = 480;
		t = (window.screen.height-h)/2;
		l = (window.screen.width-w)/2;
		
		config = "menubar=0,toolbar=0,resizable=no,scrollbars=yes,status=0,location=0,width="+w+",height="+h+",top="+t+",left="+l;
		winImprimir = window.open(url, 'popImprimir', config);
}