php กับ ajax ส่งค่าค่าภาษาไทยเป็นตัว ???? แก้ยังไงครับ

<script language="javascript">

function Inint_AJAX() {
try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) {} //IE
try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch(e) {} //IE
try { return new XMLHttpRequest(); } catch(e) {} //Native Javascript
alert("XMLHttpRequest not supported")
return null
}
//chk company user ====================================================================	
function sendget(value) {
var req = Inint_AJAX(); //สร้าง Object
req.open('GET', 'ex_ajax.php?value='+encodeURIComponent(value), true); //
req.onreadystatechange = function() { //
if (req.readyState==4) {
if (req.status==200) { //
var data=req.responseText; //
document.getElementById("test").innerHTML=""+data; //
}
}
};
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); //
req.send(null); //
};
</script>
<form action="" name="frm" method="post" enctype="application/x-www-form-urlencoded">
<label id="test"></label>
<input type="text" name="testname"><input type="button" onClick="sendget(document.frm.testname.value)">
</form>