//load our new PHPExcel library
$this->load->library('excel');
//activate worksheet number 1
$this->excel->setActiveSheetIndex(0);
//name the worksheet
$this->excel->getActiveSheet()->setTitle('Users list');

$this->excel->getActiveSheet()->getColumnDimension('A')->setAutoSize(true);
$this->excel->getActiveSheet()->getColumnDimension('B')->setAutoSize(true);
$this->excel->getActiveSheet()->getColumnDimension('C')->setAutoSize(true);
$this->excel->getActiveSheet()->getColumnDimension('D')->setAutoSize(true);
$this->excel->getActiveSheet()->getColumnDimension('E')->setAutoSize(true);


$this->excel->getActiveSheet()->getStyle("A1:E1")->applyFromArray(array("font" => array("bold" => true)));

$this->excel->setActiveSheetIndex(0)->setCellValue('A1', 'ID');
$this->excel->setActiveSheetIndex(0)->setCellValue('B1', 'FIRST NAME');
$this->excel->setActiveSheetIndex(0)->setCellValue('C1', 'LAST NAME');
$this->excel->setActiveSheetIndex(0)->setCellValue('D1', 'EMAIL ADDRESS');
$this->excel->setActiveSheetIndex(0)->setCellValue('E1', 'TIME');

// get all users in array formate
$this->excel->getActiveSheet()->fromArray($users, null, 'A2');

// read data to active sheet
$this->excel->getActiveSheet()->fromArray($users);

$filename='just_some_random_name.xlsx'; //save our workbook as this file name

header('Content-Type: application/vnd.ms-excel'); //mime type

header('Content-Disposition: attachment;filename="'.$filename.'"'); //tell browser what's the file name

header('Cache-Control: max-age=0'); //no cache

//save it to Excel5 format (excel 2003 .XLS file), change this to 'Excel2007' (and adjust the filename extension, also the header mime type)
//if you want to save it as .XLSX Excel 2007 format

$objWriter = PHPExcel_IOFactory::createWriter($this->excel, 'Excel2007');

//force user to download the Excel file without writing it to server's HD
        ob_end_clean();
$objWriter->save('php://output');