更改上传文件名 php

我在更改上传文件名时遇到问题。我希望 de 文件名是 1.pat 对于第一次上传 2.pat 对于第二次等等。我该怎么做？（"plaatje"在荷兰语中的意思是图像）

<?php
function patuploader()
{ 
echo '
    <div id="uploadForm">
    <form action="'.$_SERVER['PHP_SELF'].'" method="post" enctype="multipart/form-data">
        <label for="plaatje">Plaatje:</label>
            <input type="file" name="plaatje" id="plaatje" /><br />
        <label for="submit"></label>
            <input type="submit" name="submit" id="submit" value="Verstuur bestand!"       /><br />
</form>
</div>
 ';

 if(isset($_POST['submit']) && isset($_FILES['plaatje']) && $_FILES['plaatje']           ['type']=="application/octet-stream"){
move_uploaded_file($_FILES['plaatje']['tmp_name'], './upload/'.time().''.$_FILES['plaatje']['name']);
}elseif(isset($_FILES['plaatje']) && $_FILES['plaatje']['type']!="application/octet-stream"){
    echo '<span id="warning">it's not possible to upload this file. you can only upload .pat files.</span>';
}
# Lees de inhoud van de map uit
$bestandenRij = scandir('./upload');
$bestandenRij = array_reverse($bestandenRij);
foreach($bestandenRij as $bestand){
    # Toon alle bestanden anders dan . (localdir) en .. (magic escalator)
    if($bestand != '.' && $bestand != '..'){
        echo "'t<img src='"./upload/".$bestand."'" width='"20'"/><br />'r'n";
    }
 }
 }
 ?>