trieda phpexcel -> problém s diakritikou

<?php

require "class/PHPExcel.php";
require "class/PHPExcel/Writer/Excel2007.php";
date_default_timezone_set('Europe/Bratislava')
;
$dokument = new PHPExcel;
$dokument->getProperties()->setCreator('Martin M.');
$dokument->getProperties()->setLastModifiedBy('Martin M.');
$dokument->getProperties()->setTitle('abcd');
$dokument->removeSheetByIndex(0);

$stlp = array('B' => 'A', 'C' => 'B', 'D' => 'C', 'E' => 'D');
$str = $dokument->createSheet();
$str->setTitle('ABCDE');
$str->getColumnDimension('A')->setWidth(30);
$str->getColumnDimension('B')->setWidth(20);
$str->getColumnDimension('C')->setWidth(20);
$str->getColumnDimension('D')->setWidth(20);
$str->setCellValue('A1', 'B');
$str->setCellValue('B1', 'C');
$str->setCellValue('C1', 'D');
$str->setCellValue('D1', 'E');

$ulozisko_surov = mysql_connect("localhost:3306","xx","yy");
$db = mysql_select_db("zz", $ulozisko_surov);

$zmes = mysql_query("SELECT * FROM abcd");
$riadokpoc = 2;
$str->getDefaultStyle()->getFont()->setName('Arial')
                                   ->setSize(10);
                 
while ($surov = mysql_fetch_assoc($zmes)){
$str->setCellValue('A'.$riadokpoc, $surov['b']);
$str->setCellValue('B'.$riadokpoc, $surov['c']);
$str->setCellValue('C'.$riadokpoc, $surov['d']);
$str->setCellValue('D'.$riadokpoc, $surov['e']);
                   
$riadokpoc++;
}

$zapis = new PHPExcel_Writer_Excel2007($dokument);
$zapis->save('doc/abcd.xlsx');

print 'Ty vole, je to vyexportované.';

?>

mysql_query("SET NAMES 'utf8'");