date = new DateTime ();
$date = $date->getTimestamp();
$filename = 'REPORTE_USUARIOS_' . $date . '.xlsx';
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="' . $filename . '"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($this->excel, 'Excel5');
ob_end_clean();
$objWriter->save('php://output');