PHP变换国际编码

if(isset($_GET['order_id']) && $_GET['order_id']!==''){
					$oid=$_GET['order_id'];
					$result=$db->Execute("select `d_no` from `delivery` where `oid`=".$oid);
					$delivery_no='';
					if($result->RecordCount()>0){
						while(!$result->EOF){
							$delivery_no=$result->fields['d_no'];
							$result->MoveNext();
							}
						if($delivery_no!==''){			
								$html=file_get_contents('http://tracking.post.japanpost.jp/service/singleSearch.do?searchKind=S004&locale=ja&reqCodeNo1='.$delivery_no);	
								if($html){
									preg_match_all('/<table[^>][^>]*>(.*?) <\/table>/si',$html,$tables); 
									unset($tables[0]);
									function getUTFString($string){
										$encoding = mb_detect_encoding($string, array('ASCII','UTF-8','Shift-JIS','GB2312','GBK','BIG5'));
										return iconv($encoding,'UTF-8',$string);
										//return mb_convert_encoding($string, 'utf-8', $encoding);
									}
									echo getUTFString($tables[1][4]);
									}
							}
						}
					}