get textbox from a html table cell

Hello, I have a problem to access the input( a simple TextBox ) from html table cell. Here is a little example of structure from my Table:

<table>
  <tbody>
    <tr id="row_1">
      <td ="description" >Here is the input number 1</td>
      <td>
    </tr>
    <tr id="row_1">
      <td ="description" >Here is the input number 1</td>
      <td>
    <td id="input_cell_1">
        <input id="input_1" type="text" >
      </td>
    </tr>
    <tr id="row_2">
      <td ="description" >Here is the input number 2</td>
      <td>
      <td id="input_cell_2">
        <input id="input_2" type="text" >
      </td>
    </tr>
    ...........
    
    <tr id="row_n">
      <td ="description" >Here is the input number n</td>
      <td>
      <td id="input_cell_n">
        <input id="input_n" type="text" >
      </td>
    </tr>
  </tbody>
</table>

I have tried the Find and FindChild methods, but I get this error message: "This Object do not support this property or methode.".

Here is the funktion that I wrote:

function GetACellTextBox(myTable, cellIdStr)
{
	if(myTable!=null)
	{
		if(aqString.Compare(cellIdStr, "", false)!=0)
		{
			var tBody, tRow, tCell, tInput;
			for(var t=0; t<myTable.tBodies.length; t++)
			{
				tBody=myTable.tBodies.item(t);
				for(var i=0; i<tBody.rows.length; i++)
				{	
					tRow=tBody.rows.item(i);
					for(var j=0; j<tRow.cells.length; j++)
					{
						tCell=tRow.item(i).cells.item(j);
						tInput=tCell.Find("tagName", "input", 5);
						if(tInput!=null)
						{
							// compare the idString with cellIdStr
                                                        // if equals then return tInput;
                                                        // this is not the problem
						}
					}
				}
			}
		}
		else Print("GetACell: cellIdStr is NULL.")
	}
	else Print("ClickOnACell: Object "+myTable+" is leer.");
	return null;
}

I can not use Find Methods for tRow and tCell, because I get the same error message again and again.

What I search for is something like this tCell.GetContent() or tCell.firstChild. And yes, I can use the Find Methode like this myTable.FindAllChildren("tagName", "input", 50), but this is not ok for me.

Is it possible to get the content from a html table cell?

I really appreciate any help you can provide.