How to automatically update content in Thickbox [#303988]

I try to use Thickbox to display an image with automatic refresh.

I have the following line in a Drupal page:
<p><a title="name..." class="thickbox" href="html/chart/chart.html?height=600&width=800">TEXT</a></p>

My html file it refers is like this:

<html>
  <head>
    <meta http-equiv="refresh" content="15">
  </head>
<body>
<img src="http://www.example.com/charts.gif" width="800" height="600" />
</body>
</html>

The image displays correctly, but it doesn't update.

If I open the html page in another tab of my browser, that page refreshes itself correctly.
Also, if I go back to the Drupal's tab, the chart in Thickbox also refreshes the image (till I leave open the just opened new tab).

What may I have to do to get the contents refreshed in thickbox without need to open another tab with the referred html page?

So, how can I display a page in Thickbox with refresh capability?
Thank you for answers.