RDP screen go black after 10 min

We have a thin client that makes connection with a Terminal Server 2008 R2 RDP server.
The client opens a web page on a screen to display statics while the people are working. The strange thing is when after 10 min nobody touch the mouse or keyboard, the screen go black. When someone touch a button on the keyboard, the screen is there again. How can I disable that the screen go black?

Thanks.