jquery css display:visible none รายละเอียดด้านในครับ

<script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.js"></script>
    <script type="text/javascript">
        function Show_Div(Div_id) {
            if (false == $(Div_id).is(':visible')) {
                $(Div_id).show(250);
            }
            else {
                $(Div_id).hide(250);
            }
        }
    </script>

<?php 
 if($pageno!='0'){ 
     foreach($navigate[0] as $result){
        $navigate[4]++;
        $color_line = ($ix%2)? '#EEEEEE':'#FCFCFC';
        echo' <tr onmouseOver="javascript:this.bgColor=\'#FEED89\'" onmouseOut="javascript:this.bgColor=\''.$color_line .'\'" bgcolor="'.$color_line .'" 
                style="cursor:pointer;" class="TableDetail">
                  <td align="center">'.$navigate[4].'</td>
                  <td>&nbsp;&nbsp;'.$result['mName'].'</td>'; 
                  echo '<td align="right">'.$result['c'].'&nbsp;&nbsp;&nbsp;</td> '; 
				  echo '<td align="center"> <input type="button" value="แสดง" onclick="Show_Div(Div_1)" /></td>';
         echo '</tr>';

		echo '<tr>
		<td></td>
			<td>
			<div id="Div_1" style="display: none; background-color: #ffffdd; width: 300px;">
        I am div
    <br />
        Now you can see me.
    </div>
			</td>
		</tr>';
  $ix++;
        }