Unicode Json Encode issue in PHP
===

in my database, it has some unicode character and when I :

    $result=mysql_query($query) or die(mysql_error());
		
    while ($row = mysql_fetch_assoc($result)) {
	$response[] = $row;
    }
    echo json_encode($response);

The result is 

**[{"id":"151","titlenews":"iPad2 ? iPhone Mini ????????????? ???????????????? Samsung Galaxy Tab","photo":"ipad_1294990020.jpg"},{"id":"153","titlenews":"???????????????????????? iPhone 5 ??????????????????? Apple","photo":"iphone-5_1294996201.jpg"},{"id":"154","titlenews":"Android ??????????????????????????????????? ????????????????????????????????????????????????????? 2010","photo":"android_1295234852.jpg"}]**

Why it has "?", it should encode to any special character represent the unicode.

Thank